Although these days it is not absolutely necessary to join a cycling club to start doing time trials, it remains the best plan. I think most of the regulars on this thread are more West London, but with any luck there's some eastern types reading who can make a pitch for their own club.
http://www.ctt.org.uk/ is the controlling body, and they have pages of advice for beginners as well as full lists of events and affiliated clubs.
Although these days it is not absolutely necessary to join a cycling club to start doing time trials, it remains the best plan. I think most of the regulars on this thread are more West London, but with any luck there's some eastern types reading who can make a pitch for their own club.
http://www.ctt.org.uk/ is the controlling body, and they have pages of advice for beginners as well as full lists of events and affiliated clubs.