The most common reason people give for not investing isn't that they don't want to. It isn't that they don't understand the principle. It's that they think they don't have enough money to start. 'I'll start when I have a few thousand saved up.' 'I'll start when work settles down and I can focus on it.' 'I'll start next year when I've cleared the credit card.' I said all of these things myself, for years. They cost me more than any bad investment ever did.
Here's the truth that took me far too long to learn: you don't need thousands to start. You don't need hundreds. £100 is enough. Actually, £50 is enough. Actually, some platforms let you start with £1. The minimum is a psychological barrier, not a financial one. And the cost of waiting until you have 'enough' — however you've defined that in your head — is almost certainly higher than the cost of starting small today.
Let me show you the maths, because the maths is what finally convinced me. This is purely illustrative — investment returns aren't guaranteed and the past doesn't predict the future. If you invest £100 and add £100 every month, earning an average of 7% a year (not guaranteed — just a hypothetical for illustration), after 30 years you'd have roughly £122,000. If you wait five years to 'build up a pot' and then start with the same £100 a month, you end up with roughly £81,000. Those five years of waiting — of not starting because £100 'wasn't enough' — cost you about £41,000. The starting amount was never the problem. The waiting was.
And here's the thing: £100 a month might be too much for you right now. Or it might be too little. The exact number doesn't matter. What matters is the habit. Starting — with whatever you can afford, on whatever schedule works — is worth more than waiting until you can start with a 'proper' amount. The best time to plant a tree was 20 years ago. The second best time is today. Investing works the same way.
So how do you actually do it? How do you go from 'I'd like to start investing' to owning a slice of the global economy, with £100 or less, this week? Let me walk through exactly how I'd do it if I were starting today. This is based on what I use personally — but it's not a recommendation. Different platforms suit different people, and you should do your own research.
Step one: choose a platform. In the UK, several platforms let you start with tiny amounts and pay very low (or zero) trading fees. Trading 212 lets you open a Stocks and Shares ISA with no minimum deposit and buy fractional shares — meaning you can own a piece of Apple or Microsoft for as little as £1. InvestEngine focuses on ETFs and also has no minimum. Vanguard has a £500 minimum lump sum or £100 a month for their own funds. Freetrade offers commission-free trading with fractional shares. eToro lets you copy other investors' portfolios. These are just platforms I'm aware of — some I use, some I don't. None of this is a recommendation. Platforms change their fees, features, and terms regularly. Always check what's current before you sign up.
The key thing to look for in a platform when you're starting small: no account fees for small portfolios (some platforms charge a percentage that eats your returns when your pot is tiny), no minimum deposit (or a very low one), access to fractional shares or ETFs (so your £100 can buy a piece of expensive shares like the S&P 500 rather than being limited to cheap individual stocks), and FSCS protection (the Financial Services Compensation Scheme protects up to £85,000 of your investments if a platform fails — always check this before you hand over money).
Step two: open a Stocks and Shares ISA. This is the single most important structural decision you'll make as a beginning UK investor. An ISA is a tax wrapper — it sits around your investments and means you pay zero tax on any growth, dividends, or profits, forever. No capital gains tax. No dividend tax. No income tax. The allowance for the 2026/27 tax year is £20,000. You don't need to use all of it — you can open an ISA with £100 and add more later. The ISA is not the investment itself. It's the container. Inside it, you hold whatever you choose to invest in — shares, funds, ETFs, bonds. But the container keeps the taxman's hands off whatever happens inside.
A quick but important note: from April 2027, under-65s will be limited to £12,000 a year in new cash ISA subscriptions, with the remaining £8,000 of the £20,000 allowance needing to go into non-cash ISAs — which typically means Stocks and Shares. The government is actively encouraging people to invest rather than sit in cash. If you've been keeping your ISA money in cash because you're nervous about investing, the system is increasingly nudging you toward at least considering the alternative. Whether that's right for you depends entirely on your circumstances and risk tolerance.
Step three: pick what to invest in. This is where most beginners freeze. The choices seem overwhelming — thousands of shares, hundreds of funds, names you don't recognise, jargon you don't understand. Here's what I'd do if I were starting today with £100: buy a single broad global ETF. One fund that owns thousands of companies across the world. That's it. No stock picking. No researching individual companies. No trying to figure out whether Tesla is overvalued or whether Nvidia still has room to run. One fund. The whole world. Done.
What does that look like in practice? An ETF — exchange-traded fund — is a basket of investments that trades like a single share. A global all-cap ETF owns a slice of thousands of companies across developed and emerging markets, large-cap and small-cap, all in one fund. Popular examples include the Vanguard FTSE All-World UCITS ETF (ticker VWRP for the accumulating version) and the iShares Core MSCI World UCITS ETF (ticker SWDA). These are just examples — not recommendations. They're ETFs I'm aware of, and in some cases hold. Which one is right for you depends on your circumstances, goals, and research.
The beauty of the single-ETF approach is its simplicity. You buy one thing, regularly, and you're diversified across the global economy. If Apple has a bad quarter, you barely notice — it's one of thousands of holdings. If the US market underperforms for a while, you're also invested in Europe, Japan, emerging markets, and everywhere else. You've outsourced the stock picking, the country selection, and the sector allocation to a fund that costs about 0.07% to 0.22% a year. For that tiny fee, you own a piece of the global economy. That is, to my mind, remarkable.
Step four: set up a regular investment. This is the step that actually makes the difference between 'I opened an account' and 'I'm building wealth.' Most platforms let you automate: pick an ETF, choose an amount (£25? £50? £100?), select a frequency (monthly is standard), and the platform does the rest. The money leaves your account, buys the ETF at whatever the price happens to be that day, and the shares sit in your ISA quietly compounding. You don't need to check the price. You don't need to read the news. You don't need to do anything. The system does the work while you get on with your life.
Automating has a second benefit that's less obvious but arguably more important: it removes you from the decision-making process. Left to your own devices, you'll buy more when you're feeling confident and skip months when you're feeling nervous. Auto-invest doesn't have emotions. It buys in bull markets and bear markets, at all-time highs and during crashes, every month like clockwork. That consistency — buying through the dips as well as the peaks — is what pound-cost averaging is all about. You buy more shares when prices are low and fewer when they're high, automatically, without having to make a single judgement call about whether 'now is a good time.'
Step five: ignore it. Genuinely. Once the auto-invest is set up, once the ISA is open, once the ETF is chosen — your job is to leave it alone. Not check the price every day. Not read earnings reports. Not worry about whether the market is 'overvalued' or 'due for a correction.' The primary skill of successful investing isn't analysis or timing. It's patience. Doing nothing, consistently, for decades. The auto-invest handles the doing. Your job is to handle the not-un-doing.
A quick word on fractional shares, because they're the piece of technology that makes starting with £100 possible and they didn't exist when I started investing. Fractional shares are exactly what they sound like: you buy a fraction of a share rather than a whole one. If an S&P 500 ETF costs £80 per share and you want to invest £100, fractional shares let you buy 1.25 shares. Without fractional shares, you'd either have to save up until you can afford a whole share or buy something cheaper — neither of which is ideal. Fractional shares mean you can be fully invested with whatever amount you have, rather than leaving cash sitting in your account waiting until you can afford whole units.
Some platforms offer fractional shares; some don't. Some offer them on ETFs but not individual stocks. Some offer them on everything. The availability changes, and it's worth checking before you open an account if fractional investing matters to you. For me, with small regular contributions, it matters a lot. I don't want £23.47 sitting uninvested in my account because the ETF I want costs £80 and my monthly contribution is £100.
The biggest barrier to starting isn't knowledge. It isn't money. It's the belief that you need more of both than you actually do. You don't need to understand the difference between accumulating and distributing ETFs. You don't need to know what the CAPE ratio is or whether the yield curve is inverted. You don't need a degree in economics or a Bloomberg terminal. You need £100, a platform, an ISA, a broad global ETF, and the patience to let time do the work.
I started too late, with too little, and I was inconsistent for too long. If I could go back and give my 25-year-old self one piece of financial advice, it wouldn't be 'buy Apple stock in 1985' or 'short the housing market in 2007.' It would be: 'Open an ISA. Put in whatever you can afford — even £25 a month. Buy a global index fund. Automate it. And then get on with your life and don't touch it for 30 years.' That one piece of advice, followed consistently, would have been worth more than every stock tip and every 'can't-miss' opportunity I ever chased.
If you've been waiting to start — waiting for the right moment, the right amount, the right level of knowledge — consider this your permission. You know enough. You have enough. The first step is smaller than you think, and the cost of not taking it is larger than you realise.
For educational purposes only. Nothing here is financial advice or a recommendation to take any financial action. Platforms and ETFs mentioned are for illustration only — not endorsements. All investing carries risk. Investments can go down as well as up and you may get back less than you put in. Past performance does not guarantee future results. ISA rules can change. The £20,000 allowance and cash ISA cap are for the 2026/27 tax year. Fractional shares may not be available on all platforms or for all securities. Always do your own research and speak to a qualified financial adviser for advice tailored to your situation.