I did the L2B 20 odd years ago and i promised myself then that I would't do it again. Too many people, too many who can't really ride a bike ie. stopping in the middle of the road at the first small incline, it took me over 6 hours to do it, when it should really be around 4. There are many better rides to do. The london to Cambridge for example, last sunday of July.
http://www.bike-events.com/Ride.aspx?id=238
http://www.bike-events.com/Ride.aspx?id=238