Just tracking something down now.. doesn't appear to be a whole lot of car parks round M40 junction 12 which is the gaydon exit, the main car parks seem to be around the heritage centre itself.
I would suggest that those coming down from the North meet at Warwick Services, those coming up from the South Meet at Oxford services and i'll try and find something near to gaydon.
Looking at google maps there appears to be a couple of roads coming out of the Northbound and Southbound Areas at warwick services but I'm not sure if we're allowed to use them if we could we could nip across from one service area to the other! I'm going to give warwick services a call
