There's a discussion forum at
www.hendonmob.com where you can post your query. You'll get lots of tips.
Most of the hold 'em they spread in England is pot limit. Very hard to find a limit game but there are several clubs spreading PL in London. You have to pay a small fee to join the casino/club and be warned, after you've filled out the application there's a 24 hour wait before you can enter the premises so best do it all in advance. There also used to be a dress code, but it wasn't hugely formal. Good luck.