If you're not planning to invest alot and not wanting to devote too much time to study the markets, you can buy the ETFs (Exchange Trade Funds). They move with the general indexes, depending on what the fund are composed of (ie. biotech, semiconductors, Dow, etc). They may have these on the UK as well. Ask around. The idea is if you have a general idea of how the economy is doing, then it's easier to know the likelihood of the market direction. Never have to worry about individual stock surprise (i.e. earnings announcements, good and especially bad), the one you pick may go down due to a bad earnings news while the rest of the markets rise like cream. Hope that helps.
Good luck.