You might want to speak to Paul from RevivaUK (revivauk.com) about this. If your Centre of Main Interest (CoMI) is Spain then you would need to declare BR in Spain however you may be able to make a case that you only work in Spain and the UK is still your CoMI.
I agree with Gettingoutofdebt, you need to take advice, and Paul from Reviva is highly recommended. You can find his details in the experts section at the side of the page.
Tomorrow is a mystery, yesterday is history, today is the present, a gift to make the most of.