Your instinct re a university press sounds right to me: If the resort were in the U.S., that's exactly the kind of book an American university press would consider.

I don't know the British system well enough to speculate.

But I'm not sure you should write off American university presses and think only of Britain, where there are so many fewer of these presses. In your situation I might try to get a sense of how open the U.S. university presses are to overseas authors, given that they would vastly expand your options.

Someone who might have an idea is @JimFonseca, an author and retired geography professor. Will let you know if I think of others, but he's the one who leaps to mind now.