I had the same problem with the worldbuilding (to be fair, I have this issue with alternate history in general), and later books didn't really address it. They're good fun when there's enough action taking place to keep everything moving briskly, but when the plot slows down enough that I have to think about the background, I get thrown out of the story by a chain of "But if... that doesn't make any sense..."

This is not a widely shared opinion, and the later books do visit a wider range of places that are changed much more significantly by the presence of dragons. To me, that just highlights the problems with the lack of changes in Britain, but again, not a widely shared opinion.