You make some great points. No, I can't think of any current fantasies inspired by British/Celtic folklore at the moment.

...I'm going outside my box with what I'm writing at the moment (put to one side while I get on with writing my museum exhibition)because it's a science fiction children's story involving about a boy and a girl from a Chinese village. I wanted to write for my nephew so he can read something about a boy like him. So far the feedback has been good on the early stuff, but I'll be getting it checked out with my extended family as it progresses.