Alton is the closest town (less than 10 minutes drive), with direct trains to London Waterloo in just over an hour. There are many taxi companies in Alton who can be pre-booked for collection from the station.
Guildford is a half hour drive (there is a bus service from Alton to Guildford) with direct trains to London Gatwick Airport.
For drivers, Upper Farringdon is located off the A32, approximately an hours drive from South London.