You need to find a decent stockbroker. Most banks will have one in your local branch. They will charge you a commission for acting as an agent.
Unless you invest large amounts of money £millions, don't expect to make anything out of the dividends (assuming it makes profit).
If the price goes up, you sell and keep the difference, less broker charges... If the price goes down, you either sell at a loss or keep until the price goes back up.
If I were you I'd think very carefully before investing your savings. ANY investments should be money you can AFFORD to risk losing.
The institutional investor wants short term gain, so will more often than not, go for high dividend payers; but these shares are ususally expensive for this reason. You are up against investors who have experts on massive wages trying to predict future changes... It isn't easy.
I have once made a good return on an investment, and also made a series of small losses...
If you are looking to buy a few hundred quid of shares for the fun of it, then I'd say go for it... But only for fun unless you know what you're doing.
EDIT: The LSE had a simulator, where you entered in your purchases and sales and it would calculate your profit/loss based on real world share price changes... It was to help joe public understand the stock market and see how they would fair if they tried it.
