I live & work in London at the moment - so let's call it "home". London is one of the most expensive cities in the world. That's good in one way, since just about anywhere you go things are cheaper than what you're used to.
Back to the important things. There are hundreds of breweries throughout the UK, too many to list here. They produce mainly ales & bitters, of which I’m not too fond. I’m more of a lager drinker. You know… cold beer that does not have a flat taste.
As far as lager goes, it’s mainly overseas beers (produced under licence in the UK) available in pubs and stores. Stella Artois (5% vol. – Belgium), Fosters (4% vol. – Australia) Heineken Cold Filtered (3% vol. – Holland), Kronenbourg (5% vol. – France) and Carlsberg (5% vol. – Denmark) is probably the most common ones found (on tap and bottled/canned in shops). The locally produced Fosters is apparently much better than the real thing from Australia, according to all the Aussies. All other famous world brands like Budweiser, Grolsch and Becks are widely available.
One thing I urge you to try is a Snakebite (half beer, half cider with a bit of blackcurrant cordial). Please note that it’s not normally served in the traditional English pubs, you’d be better of asking for it in any of the Antipodean / South African theme pubs (of which there are plenty).
Beers cost anything from about $0.85 (Skol Lager) to about $1.45 (i.e. Heineken Export) for a 500ml can in an off licence. Expect to pay about $2.60 - $3.00 for a pint in pubs and as much as $5.00 for a 330ml bottle in London nightclubs. When in London and on a budget, consider going to any of the abundant JD Whetherspoon’s who sometimes have £1 ($1.43) specials on some bottled (250ml) beers. As one moves out of London into the country, prices do drop quite a bit.