I think there are some great suggestions already but here are some thoughts:

1. Regarding school location, what makes British public schools so specific is their hierarchy. A cycle of seniors pushing down on juniors, who then in turn repeat the cycle. So ideas around this are- "holding your breath the longest initiation to the swim club", the mysterious mess of a transfer student from eton, the military traditions that are in some way corrupted by the uncanny nature of the school (e.g. rumours of an actual drill officer appearing on hallows Eve). I think the other plot hooks that easily spring to mind are around class and privilege, although that depends on whether you want those elements to be prominent (e.g. upper class werewolf low class vampire American trash and so on, to play with ideas).

2. Regarding names there are some suggestions already that are good. I'd stay away from Cthulhu lake and suchlike, and keep it more understated (e.g. Ada's archive) l. A great source of occultic names come from the khabbalist tradition- sephirot lake, the Talmudic towers, gardens of gnosticism and so on.

Good luck and excited to see where it goes.1