You could do a lot worse than get hold of the Luath Guide 'The West Highlands-The Lonely Lands' by Tom Atkinson. He uses a curious mixture of history, geography, myth and legend and writes in a very accessible style. So for Loch Fyne you get local history and information as well as the tale of the witch who fell asleep in the sun and did not cap the well she used to water her cattle. The sweet water of the well overflowed and became Loch Fyne. I once saw two complete rainbows on Loch Fyne, it's one of the most magical lochs.