I can't help with the UK I'm afraid but if you're looking for this kind of training in the US then you could do a lot worse than Attitude Aviation in Livermore, CA (near San Francisco). As long as you do it between May and September you can be sure of good flying conditions. And you can always do what I did, and reward yourself for getting checked out on the Pitts by taking the L-39 for an outing. Beware though that getting to the point of landing the Pitts safely takes a LOT of practice - not something you can do in a weekend or even imo in a week. (No doubt this will attract lots of people saying, "Pah, call yourself a pilot, I got checked out in the Pitts in 3 flights", but that isn't most people's experience).
(I have no business connection with Attitude, although I am a satisfied customer, with 75+ hours on their S2C).
n5296s