The movie/musical Camelot gives another point of view, too. I've read some others and can't remember the names or even the author any more. I also just searched 14 bookcases for them, and couldn't find them. However, Le Morte d'Arthur would be a good starting point, if you haven't already read it. Possible recommendation is that you do an Internet search for Arthur, Science Fiction (or Fantasy) and see what pops up. Arthur has been covered a lot, and in a lot of different ways (including from Merlin's point of view). That you would tackle something like this tells me that you think you have a fresh approach, and I wish you luck with it.