Lots... A few that come immediately to mind:
Caernarfon - is there still a small museum there?
Carlisle - aviation museum including a Vulcan, Phantom, Lightning etc.
RAF Cosford (in the week?) - RAF Museum
Coventry - Midland Air Museum
East Fortune - is the strip still available?
East Midlands - Aeropark including Vulcan, Canberra, Varsity, etc, wrong side of the airport for flying to though (taxi ride round the perimeter)
Kemble - there's an aircraft museum in one of the hangars, but I'm not sure how often its open
Norwich - City of Norwich Aviation Museum on airport
Wickenby - has a small aviation museum but no aircraft
Breighton - arguably as much of a museum as Old Warden, although smaller?
I bet there's more...
Andy