I drive to BH a few times a year for various reasons from the Heathrow area. On average, and not pushing it, I leave about an hour and a quarter and am rarely over an hour. So, starting from BH in that time you could be at Fairoaks or Rochester and probably Headcorn as well and probably many other ‘smaller’ fields. Damyns Hall in enemy territory might be an option?
Think about the type of flying you want to do - why a PPL and not LAPL / NPPL(A) / Microlight and then move up if necessary. Wherever and whatever you choose, pop in and have a chat and get the feel for it - where are you comfortable and who are you comfortable with?