Just saying, you can cycle to London Bridge in 20-25 minutes from Forest Hill Station. If you count the time getting to the station, waiting for the train etc, you're always quicker on a bike.
Totally agree Clausy and I cycle into town for work virtually very day (although it's far less pleasant in the cold and rain which is undoubtedly coming), but at the weekend if you go out for drinks/dinner/party/clubs or whatever in town and you have a few drinks, you don't want to be cycling home because that's just as bad and dangerous as drinking and driving, and even if you're not drinking you're probably not dressed for cycling.