Why not try one of the local universities? That's how I found my teacher. (Now I live in the U.S. so I'm not sure about protocol at universities in the U.K. )
I e-mailed that the head of the piano department at a nearby university (well, sort of, it's about 75 miles away) and asked her advice about teachers in the area. In the e-mail, I mentioned how long I had studied, how long ago it had been since I had played, what level I had been at prior, what pieces I had played, etc. She e-mailed me back and asked me to contact her by phone. We chatted and she asked if I would be interested in studying with her. We scheduled a lesson and she asked me to prepare a couple pieces, whatever I wanted.
At the lesson I played through my Bach and Scarlatti and we worked on the pieces together, very much like I had done years before with my original piano teacher. Then we talked about my goals, how much practice I would have available (I work full time), costs and worked out a schedule. (I go every other week for an hour lesson.)
She asked me to get a notebook (I had already brought one!) and we picked out a Romantic piece (Chopin) and a modern piece (Tcherepnin) for me to prepare for my next lesson. That was almost 2 years ago. Best thing I've ever done.
Good luck in your search.