EP - are you doing the L2B bike ride or run?? I assume the bike...
if so, don't worry about too much training for it as you'll be going at snail's pace - unless you are very quick and get off as soon as the 1st riders go you can more or less kiss goodbye to having a good ride. people will walk the hillier bits and clog the roads so you have very little chance of riding up them and then there will just be a general slow procession on the roads as they are still open to traffic until you get to Brighton. with 35000 rides doing it, it's a nightmare - have done it 3 times in the distant past but never again as there are just too many riders
if it's the run - do some training!