There's a charity cycle ride starting from Leatherhead on the 18th of September that I've signed up to with two of my housemates. There are 3 routes of 13, 26 or 45miles riding through Surrey, including part of the 2012 olympic cycle routes. Proceeds go to the QEF, a charity which supports the physically and mentally disabled.

http://www.qef.org.uk/events/bikeathon-2011-announced/