Part of Alan Garner's psycho-novel 'Red Shift' deals with the collision between the Romans and the 'pre-historic' british mother goddess cults. it's a bit late for you but a very wonderful evocation of ritual landscape inspired by the axe head the author found at Mow Cop a hillfort / scared mound in Staffordshire.
His other stuff - allegedly children's books - reference prehistoric features and sacred hills a lot - Elidor (standing stones), The Moon of Gomrath (barrows), Weirdtone of Brisengamen (more stones and hills), The Owl Service (goddess culture, menhirs)
Then there is that 'Stonehenge' book by Bernard somebody or other - cheesy but if you're stuck on Lewis in a storm an interesting specualtion of how England's most famous monument came to be
And let's not forget '5 million years BC' with Racquel Welsh in a fur bra..