An EASA PPL(A) with a SEP rating is valid for all single piston engined aeroplanes, no 12,500Lbs weight limit like the FAA, in fact no weight limit at all! Not sure what you mean about the Germans giving only 2,000Kg, maybe ther are more restrictive than other EASA countries.
The Spitfire would certainly count in UK although I can understand that the flight might not get ministerial approval!! Come on down and fly our Tiger Moth and you can view and sit in the Spit afterwards!! You might see it fly if the timing is right!
Happy landings
3 Point