WelshFlyer, to answer the question you asked: yes, there are various clubs/syndicates/private companies out there offering training on the Jet Provost. See e.g.
TurboJet Training,
Swords Aviation,
Where Eagles Share and
Newcastle Jet Provost Co.. To qualify for training, it will be necessary for you to purchase a share in the aircraft (for approximately £4,000), plus you'll be responsible for monthly dues (approximately £250).
For training on the Hawker Hunter, see
Delta Jets (they also have a JP and a Gnat available, at lower cost).
I hope that this helps. If you are thinking of going for it, don't be deterred by all of the negative comments posted above. From the viewpoint of most would-be conversion pilots, the fact that the JP has less performance than, say, an F-104, is a good thing. Developing and increasing your piloting skills slowly and safely is much, much more important than impressing any of the anonymous people on this forum.