One of the problems you face is that when it comes to learning Aero's it can be remarkably difficult to find the plane you want in the area you want it so in that respect it might be a case of seeing who is closest and going from there. The majority of interesting aerobatic planes for hire are owned by individuals set up as a flying school so searching 'pitts for hire in the Sheffield area' might throw up some ideas.
So anyway my thoughts
How much, if any tail dragger experience do you have?
If you want a tricycle:
Slingsby's. I only ever flew one with a 115hp engine many years ago. Pretty anaemic on power but capable enough to learn standard aerobatics. I am sure a more powerful version would be very good for what you want.
Bulldog. I learnt in these on an air squadron. Good for standard aero's, probably better roll rate than Slingsby but view 200hp lump and vp prop will be more expensive to hire.
Grob 115.(think its the D or E) Only flown the non aerobatic B (160hp) Think they should be quite capable though.
If you can consider tail draggers then:
Cap 10 B or C. these are lovely to fly. the C has electric flaps and better rate of roll, easy to land and capable of intermediate aeros view inverted oil. as for cost, only ref I have think of is the tiger club which charges £235 per hour. I don't know about your neck of the woods or if you could find one.
Pitts as mentioned already - fantastic planes, charismatic, fun and it feels like an adventure. Not the easiest to land so if you don't have any tail dragging experience you will initially spend as much time getting to grips with the landings as with the aero's. I would think you would be paying £220+ and hour to hire one.
extra 200- pretty much same as the 300's in terms of roll rate, +/-10 G and will do virtually every manoeuvre that a 300 can but without the 300hp oomph. Easy to fly and land and handling on the ground is very benign, certainly the easiest tail dragger I've flown in that respect. Cambridge Aero club charge £255 per hour dual.
Personally, if you have the budget and can find one locally or don't mind a long drive I'd go with an extra 200.