Not been in one of TCX's 757's lately, but from what I heard you get what you pay for with your 3 hour flight.
Their A320's, on the other hand, are just damn right awful. The legroom is ridiculous and I had to spread my legs out as if I was giving birth in order to be in the most comfortable position.... which wasn't at all comfortable.
Don't see why you need the registration... it will not help if you don't provide the departure airfield, though. Just see what is there on the day as things can change with a few hours notice if aircraft are tied up here and there.
When you've landed.. preferably back at home airport.. and the engines are shut down, as a member of cabin crew if there's a chance you can visit then but remember they're often on turn arounds and busy with paperwork.
Enjoy Ibiza. The approach is good if you're on the left and landing from the East
Enjoy your holidays!
Scott