The easiest and cheapest way to buy shares is online from what's called a 'share dealing platform'. These platforms allow you to buy shares from any company listed on the stock exchange and various overseas exchanges. How to buy shares in the UK - cheap ways to invest in the stock market. The FTSE 100 is up 4.5% on this time last year, while the FTSE All Share is up 4.6%. And on top of the growth in value, this year is also set to break records for dividends - that's the payout companies make to their shareholders.