Biggin Hill isn't that scary to fly from. There's a lot of jet traffic at times though, which means GA aircraft have to orbit or hold for jets on the ILS which can get annoying, and with everyman and his dog trying to fly at the weekend, getting up in the week might be easier.
Class G airspace to the southeast of the airfield which means as soon as you leave Biggin, you can do what you like, although Farnborough Radar is available across Kent and Sussex.
I rent a C172 from Alouette Flying Club (
www.alouette.org.uk) at £100/Tacho plus landing. PM or e-mail me if you want any more details