Hey.
I've just finished four years (BA, MA) in English at UCL. Thought I'd give you a warning - a lot of us there, postgrads and undergrads, had negative experiences.
Yes, it's a very prestigious university. Don't know where it is in the league tables (they are seriously flawed, anyway), but in reality it's certainly equal to Oxbridge, if not stronger in many depts. It has an immense reputation, and if you get through a degree there you'll find a lot of career prospects opening up for you. The vast majority of their English graduates go into high-salaried jobs in law, journalism, and the like.
However, if you go to a university like that, part of the deal is that you won't find a particularly humane or supportive environment. If you're coming from a public school, and / or a very wealthy family, you'll fit right in at UCL. If not, you'd better be prepared to deal with some very arrogant, very overprivileged people. UCL is notorious for this - it is extremely selective and elitist. Similarly, although the English faculty includes some of the most famous people in the profession today, don't expect them to treat you with a great deal of respect. In fact, many of them will treat you with complete disdain. They're far too wrapped up in their own careers to care about their students.
You've been warned!!! I guess it all depends on what you want to do, anyway. If you're ruthlessly ambitious, and are looking to get into a high-powered profession after your degree, UCL wins hands down. If you're actually more interested in your subject, there are lots of options open to you. All of the different unis have different strengths and weaknesses. If you happen to be into medieval literature, definitely go to Leeds - their dept. is world-famous for that. Sussex is the best if you want to combine English with other disciplines - I'm going there for a PhD in the autumn. Warwick is a very strong all-rounder. On the other hand, UCL will give you the best educational experience you'll find outside of Oxford / Cambridge. The problem is, you'll have to be prepared to deal with a lot of wealth, privilege, and snobbery.
Hope this helps - bear it in mind, anyway!