Well the only specialist in aeros I know is at Kemble in Gloucestershire, Ultimate High. However at many airfields you could find an aerobatic instructor - certainly down in Compton Abbas in Dorset for example. My employers can provide in Bournemouth, but is not cheap as until I get the time and weather to do the course the only person qualified for aeros is the head of training. Damn good instructor though, and we have an SF 260
Anyone should be able to give UA training.