Aviano - depending when you go and depending when the proposed changes to the Italian airspace come into force, you may not have a problem there anymore, as the entire NE Italian airspace has been redesigned - MUCH better for VFR flight ! Again, I don't know when these changes will be implemented, probably too late for you (Sep/Oct).
Fuel in Lyon area - you could go to LFMH Saint Etienne. I refuelled there once some years ago and the pump is near the aeroclub building. What I cannot remember is how I paid, probably EUR cash if memory serves. There is,
AFAIK, also an automated 100LL dispenser but you need a Total card for that one. The guys in the aeroclub are very nice and helpful, perhaps give them a call (there's a link to them on the LFMH website).