Hi SAA - the plane ride might go better than you think. I stressed about it when we did Spain/Eng and back again, but actually DD was pretty good. Fed her going up and down and did the 5S thing to get her sleepy - the drone of the engines also helped. I also gave her a wee bit of paracetamol before we got the flight to guard against pressure headaches - anyway, seemed to work, she didn't have any problems.
And even if it IS a bit of a nightmare, at least it's only a short flight! The crew might let you stand with you LO in the galley area if he starts creating, they did with my DD (not that she created for long).
Also, Spanish houses tend to be well-shuttered, so you may find you can black out rooms for your DS' sleep more easily than in the UK.
Where are you off to? If you're passing Madrid, feel free to drop in (!)
Well, this last week has been better at Casa IC - my insomnia not so bad and the IBS just about ignorable. Last night was annoying 'cos I got an attack of throat-clearing necessity, which kept me awake from 0400 and I only really got a short snooze after that. DD wasn't too bad, (woke up her usual every couple of hours, but resettled quickly each time) - I really am my own worst enemy.
Oops, DD's just woken up...better go...