In reality, the only people who give a damn where you did your IR are those schools that can't afford to compete. Spain is a JAA state and satisfies the criteria and standards laid down by the JAA. If you do the CPL in the UK and the IR in Spain the IR will appear on your UK issued licence with no mention of where it was done.
Don't get sucked into the "our standards are better than your standards" debate. It's just spin.