In all seriousness: if you're not that familiar with Arthuriana, what is the attraction of trying to write a book centered around it? There are loads of flavors of Arthur stories out there. Why not pick something you already know about--or make something up on your own?

If you're really insistent on doing something Camelot-y, why not at least skip the same tired Arthur-Lancelot-Guinevere triad and follow one of the knights of the Round Table? Pick up the Arthurian Romances of Chretien de Troyes; the Penguin Classics translation is a good one. Some of those romances could supply you with a plot, I suppose.