This is making a bit of a mountain out of a molehill. I also don't see how the CAA can answer for foreign aviation authorities.
What I did (although it is irrelevant as I have both FAA & JAA licenses) is write to the various aviation authorities that concerned me - in my case it was the DGAC in France and Germany...I think I did a few more but can't remember which ones.
Anyway in each case they said "if the UK allow you to fly in their airspace, then we will too"....I'd just write to them (email) and get it in writing then keep it with you. They even said that all ratings were valid which raised an interesting point which was discussed several years ago - because the CAA validate an FAA IR for flight OCAS....how this translates to Euroland...