Brewing the ready made stuff in bags or whatever is easy, but it never tastes exactly brilliant. Ok, but not great. But then it works out at 25p a pint or something so who cares.
There's a fair amount of choice out there. There's the stuff that's all pre mixed in a bag with a tap on it, that you just pour water into, leave for a few weeks and then drink. Then there's packets of mixed malt/barley/yeast etc that you need a brewing barrel for, which you just add water to. Or you buy different bits and bobs, mix them together and chuck them in a barrel with some water.
There's even a special oojamaflip that you use to work out the specific gravity of the beer so you can tell when it's finished brewing.
My dad brews his own, and can rustle together pretty good copies of commercial ales. However, he does it with proper hops he's grown himself and yeast he's knitted from scratch out of random molecules and such like, so that's a bit more time, space and labour intensive. However, his stuff is quite fantastic, and better than a lot of commercial ones.
If you're short on space and time, you want to avoid anything that involves having to bottle the stuff - that takes aaaages. The sterilisation, then the filling, then the capping. Couple of days work for a barrel of the stuff. But then you can't really beat the home brew that's part brewed in the bottle.
But if you don't have the space for that sort of thing, and you're not buying the cheapy bagged stuff, get a brewing barrel that has a tap on it, and Robert's your mum's brother.
Best advice is to find a home brew shop - there are a surprising number of them around, and are usually run by excellently beardy be-slippered pipe smoking CAMRA members who will be very happy to give you some advice.