Cope wrote a brilliant book called The Modern Antiquarian which is half his writings and thoughts on the pre-Christian Britain era and the other half is a gazetteer to British neolithic sites which he went round in the 90s. It's a really good book but pretty expensive and I think out of print right now.
He's done another one called The Megalithic European which is a guide to neolithic sites across Europe which is in print and is also fantastic. [Edited by sabbathfan at 17:31 on 08/03/10]