U.K. PARURESIS TRUST: Long flight

Hi,
I've visited some workshops in the past, en since then i'm coping quiet ok, although mostly in cubicals.
A friend invited me on a 5 day trip to LA, sounds good, no?
If it was not for the 11 hour flight....
There's the low level of urgency, high level of anxiety issue.
I don't want to drink some fluids if i'm not certain i can go, and i'm not certain at all.
Actually, i never went on an airplane in my life.
Long time ago i also went on long flights, but i don't want do them like i used to, ie, hardly drinking fluid the night before, and on the day and the flight, almost nothing. Untill we get closer to the destination and my head aches, i started to slowly take on fluids.
I don't think this is healthy.
On top there is the US cubical, compared to the ones we have, they have zero privacy.
Door and walls not floor to ceiling, these usually elevate my problem also when i come across them in Europe.
But the flight bothers me the most.
If there is a problem on the ground, i usually come across a sollution within a few hours, as i can go to another place, find an excuse and leave or even go home if i'm having a bad day.
At 32.000 feet it's a different story...once the door is closed, remains closed for at least 11 hours...
And i don't want my friend to make a medical emergency landing because i can't empty my bladder :-)
I still have time to decide to go along or not. A few years ago i had the same offer and turned it down....