Are you still looking and what are your other requirements (age/background/breeding etc) I found my perfect 15.2 all rounder in Ireland as a youngster - gorsebridge horse sales and I know a lot of other great 15.2s that have come from there. A friend of mine breeds and has a couple of smaller...
Are you still looking for somewhere? I think it will very much depend on where you live and if you have access to a car. I know of lots of yards in Hertfordshire, North and East London if you want some info