I've gone for self-catering in the past.

Plane Food picnics are quite good options for low carbers (apart from desert, though you can have the cheese, if not the biscuits).

I seem to remember someone here once recommending the fish, but I've never seen anything which wasn't at least moderately carb-heavy.

Btw - Good luck with the diet. I avoided anything formal, but cutting down on carbs by 90% or so has dramatically changed my life!