see, when you say 'Beer is bitter and heavy' i'm guessing you've not tried all that much.... there are over 500 brewers producing more than 2500 Cask Ale in the UK.. and believe me when i say i've seen a small number of those beers, and i could still probably point you in the right direction
If you like Honey, try Waggledance, from Youngs, strong, sweet and reasonably light... a little heavier, Honeypot from Coachhouse, the clue is in the name. something lighter? try Arizona from Phoenix in Manchester, light dry, not as sweet but very easy to drink
Guinness drinkers would probably prefer a stout or porter, Salem Porter from Batemans being an outstanding example. as is Titanic Stout (which i'm drinking right now)
Lager drinkers? Scihallion, cask conditioned lager from Harvistoun in Scotland.
If you can't guess, I voted to beer, as it's such a diverse product, if can taste like... pretty much anything you want... chocolate and coffee, to citrus and honey, or dry and bitter... depending how you brew it. I've personally tried just a small spectrum of the beers that are made each year and I'm still finding out new and different beers (working in a Cask Ale pub kinda helps too)