I've been told that in Italy, a lot of restaurants will cook you pizza on your own gluten free pizza base if you ask them. Might it be worth trying that in England? Or generally agitating pizza places to provide (Pizza Express used to do one with a potato base, but I don't think they do any more.) Are you sure they *don't*? As I said, Bella Italia had an entire gluten free menu, but there was nothing on the main menu or anywhere else to say that. (They didn't actually have any gluten free pasta when I was there, so it was a bit academic, but at least the thought was there.)

Asking pubs to stock gluten free beer might also work.