The VGS has AVGAS by their hangar. I'm sure if you spoke nicely to OC OPs and also SATCO they could have you in on the Fri and ut on the Sat. The VGS have AG radio but for info only. Some regulars used to keep their GA at Odiham and fly out using the VGS to get airborn then onto F'Borough, or depart post phonecall to Farnborough. Shouldn't be too much of a problem but definatley worth speaking nicely to ops.
Jaffa cakes/Case of booze might be a suitable bribe.