Perhaps the US-based schools advertise very extensively in the UK than do other countries? Obviously the US is much closer but if you're looking for an alternative that could perhaps be a little more like home, and at a reasonable cost, NZ may be worth a look.
I might add South Africa to that as well. Thing is though I don't know of any JAA schools outside Europe that are not in America, I don't even know if any JAA schools exist outside Europe and America.
If there are then they keep fairly quite about it.