As long as you don't expect to charge British prices, I would think you could do quite well out here. There are a lot of us (Ex-Pats) that would welcome a plumber that "thinks" about a problem before trying to solve the leak, low pressure or whatever!! I AM, of course, assuming you speak reasonable to good Spanish.
If you are considering coming to the North Coast, drop me an e-mail & we can communicate further - Grahame.