Quick update on this one for anyone whos interested.. All went through fine, mostly.
Checking it in at Luton was no problems, they didn't bat an eyelid when I told them what was in it.
When it got to Lisbon I noticed a couple of things. The tape had been completely removed at the ends and the screen had definitely been removed from the pipe at least once. I don't know if the tape had broken and they had to repack it...but either way it had been out of the pipe at least once on its trip.
I'm not complaining though. No questions were raised with it at all. The screen is now in my apartment waiting to be fitted to the ceiling. It picked up one mark on the casing but nothing to make me think the screen itself is damaged.