Leeneia, it appears there are now also Gentle ebooks. It may be this allows to extend your collection even further. Still, it may be just the originals matching the TV-series episodes, which would mean they miss something like half the stories.

The stories seem to play in Norfolk, but I don't know whether Gentle's station is further inland. Maybe some of the stories give more information on that. If it's not on the coast, you'd expect Starmouth to be (Great) Yarmouth. Before the place was auto-demolished, by it's own authorities, the inner city of Great Yarmouth didn't have real street names; the rows were still named by the "what people say to refer to them" system. I can of think of different ways to read the name "Kittle Witches", but the important part in a mock-Yarmouth is probably that it's the current nickname for a row in the old centre.

BFN
Mysha