With a bit of google searching I have found six ATOs in the UK offering the Advanced UPRT course, there may be others I have missed. I presume they all have met the same CAA requirements so I don't know how they could be ranked in any particular order of merit (short of personally evaluating each one).
I suspect Rottweiler22's course may not have been in the UK (not so many F-16 pilots here). There is a UPRT school at Breda in the Netherlands which is a branch of an American UPRT company, but they claim to be the best in the world so perhaps not that one either.