Try "the home of champions"!!
Hello,
Your best chance for seeing some world-class pool (and sometimes snooker) will be at the club that everyone here in the UK calls "the home of champions". Riley's Victoria (right next to Victoria train and coach stations in London). If you're lucky you could get to see Steve Knight, Imran Majid, Tony Drago, Raj Hundal, Ronnie O'Sullivan, Jimmy White and Rico Diks plus a whole host of great semi-pro players. The club also has the nicest management you'll ever meet although you will probably have to join up as a member even if you don't play. It's not cheap (nothing in London ever is) but it's an amazing place. Also there's a good club in Cambridge called Mickey Flynns which is well worth a visit if you're in that area. I second the Pro9.co.uk recommendation. You'll get all the info you need there.
Hope this helps,
Chris (Chrstc).