I've been commuting by bike for a long time. I could not do without it. Echo all the advice above, regarding training and bike skills. Also a huge recommendation for the Bike Safe course with the police. Believe it or not, during normal commuting times you don't often need proper wet weather gear. No waiting for buses, no waiting for trains, don't have to worry when everyone at works is citing train cancellations...gives you massive freedom. Would also echo someone's comments above - from SE22 to the city, almost no difference in commute time between a motorbike and a bicycle. I do find the moto much more pleasant through winter though. Go for a 250cc scooter (125 is big enough for commuting but a pain for longer trips, especially A roads or motorways). And lock it up. Buy the best chains and locks you can, and a ground anchor.