Fun, relaxed dance classes.

Hi all.
My son is on the autistic spectrum & has just started reception. He loves dance & movement & I'd like to enrol him in some kind of very informal dance class...the problem is that he's likely to dip in and out of instruction and want to do his own thing some of the time. I want it to be fun and sociable for him and I dont want to worry about him being disruptive. Does anyone know of anywhere I could try near amersham?
Thank you very much!