Thanks for the feedback guys. I spent hours trying to find a decent background for this. Because the colour scheme on the map is so light, a dark background made it pop more.
I was trying to get a sense of drama into the map - 'Stormlit cloister' suggests to me deep, bright sunset like reds behind a mountain - hence the choice of the colouring of the Title.
And then I went a bit mad with super saturated colours which really stand off the page!, but you're absolutely right, the map gets lost among all the other elements.
I think I might try again with the composition and make a series of different choices on how to present the map.