It's getting close to the right time of year to be flying open-cockpit, too....
Harrumph... Really, FFF, I flew the Northants School of Flying's Tiger, at Sywell, during both January and February and if it's not actually raining it's perfectly pleasant for 30 minutes or so providing you're properly wrapped up. (Also it's a particularly nice Tiger with a more powerful Chipmunk engine so it goes rather well).
I think the assertion that a 150hr PPL can be no more than a passenger in the T-6 is rather pessimistic. True, if you're not already tailwheel qualified you might not be doing takeoffs and landings, but there's no reason why you couldn't do some general handling. If the instructor is any good, you could learn a lot. I agree, however, that if you've not flown anything tandem and tailwheely before, a Moth, Cub or Chipmunk is as good a starting point as any. Another nice taildragger is the Super Decathlon, I think there's one at Tatenhill, which is not too far fom Oxford.