I do, but not in O. We have a small OO (1:76) layout in the garage that is all British prototype, and I have several odds and ends in N, but no layout yet. The British O scale stuff is too rich for my blood. A good place to start is Hattons. They ship to the US without complaint and have a decent variety of O, though far more in OO and N.
There are also several small kit makers over there, though you really have to search them out. I can highly recommend checking out British Railway Modelling and Peco's Railway Modeller. (Yes, it's really spelled that way.)
Cheers!
Fred