Most of the retellings of Arthurian legends that I’ve read are set in southern England or Cornwall. George Finkel’s Twilight Province is set primarily in the northern part of Britain just past Cataractonium (now Catterick in Yorkshire). Additionally, the story is narrated from the point of view of Bedwyr much like Gillian Bradshaw’s Hawk of May is told from the point of view of Gwalchmai ap Lot (AKA Gawain).
Fortunately, Twilight Province includes several detailed maps, but also includes a map Bedwyr purchases while abroad. He says this about the map:
“While a map is not an infallible guide to a traveller, in a strange country it is better than no guide at all. If it does not show the distance between one place and another, at least it shows their relationship regarding direction. Since there are ways, know to every boy in Britain, of finding the North — from the way moss grows on tree-trunks, for instance, or from Polaris in the constellation of the Bear — and it is known from the map that Ratae lies due north of Veralamium [sic], one at least knows in which direction to set off.”
– pages 114 and 116
