Easy option - ride across london to Herne Hill Velodrome.
http://www.hernehillvelodrome.co.uk/

Have great training sessions every saturday morning (track should be open by now). Used to ride from Hackney to train and race there. You will get so much fitter, stronger and faster.


And then ride there on good friday for the annual Good Friday Meeting (Friday 6th April). World class field racing (well it has Bradley Wiggins, Rob Hayles etc)
http://www.goodfridaymeeting.org.uk/