In the end, that became an easy choice. I have connections with Cornwall, and used to holiday there each summer as a kid. In later life I would often drive along the north coast between Sennen and St Ives. En route, between Zennor and St Ives is a spectacularly lonely stretch of road where there is a very small hamlet with a house on a high promontory over looking the sea. It is here that I imagined the school to be. In fact all there is, is a farm and some farm buildings. The design of the school is based on my old school which indeed was a converted farm and a large house built around a quadrangle. Our gym and dining hall were both in converted barns and the changing room was a dark labyrinth underneath another barn.
Anyway, late last year I braved the six mile Zennor to St Ives walk twice, once along the coast and once along "The Coffin Path" (it does exist). Six miles and four hours of solid slog.
This stream probably originates on Trendrine hill which lies the other side of the road.
If anywhere is chapel cove, this is it! In reality, Chapel Cove was based on a cove near Swanage in Dorset.
Wicca does exist as a place, that is closest to the location I chose.
If you have not already worked out, lots of weirdness takes place in Cornwall. I was there during the eclipse in 1999, we saw nothing, it was thick black cloud and raining, when the sky darkened, it was the proverbial end of the world to look at. Didn't stop the local farmer from ploughing though!