Believe it or not, there are some scholars who believe the prototype of Camelot was indeed in southern Scotland, as a result of attempting to identify the historical figure on whom the legendary Arthur was based.
Arthurian fiction I've read:
Tennyson's Idylls of the King, and related poems
parts of Geoffrey of Monmouth
White--The Once and Future King
Stewart's first 3 books (I have The Wicked Day but haven't read it yet)
Charles Williams's Arthurian poetry
parts of Malory
parts of Chretien de Troyes
the Mabinogion material
Bradley--The Mists of Avalon (not the other one yet)
(author forgotten)--The Idylls of the Queen (about the insult to Guinevere, from Kay's point of view)
and some others I can't remember at the moment
I have the Lawhead books but haven't read them yet either.
Thay all have their good points and they're all quite different from each other!