The EBU (English Bridge Union) is the regulating body for the game (the courts recently decided it couldn't attract the tax breaks of a sport). Clubs don't have to belong to the EBU and do have to pay for the privilege. Membership for individuals is free, if they play at EBU clubs.

Amongst other expected regulatory tasks the EBU runs a comprehensive ladder scheme the National Grading Scheme called NGS on their web site. This gives a good estimate of the current form of members. You can search for an EBU club from their web site. The general standard in clubs varies: clubs with a lower NGS standard are more suitable for inexperienced players. Information about the average NGS of a club is known to the club but not often published. As far as I am aware, the lowest NGS local club is Orpington Bridge Club which has a fair number of inexperienced players.