Wouldn't it be easier, once the stewardess pass around with the menu card, to say "no thanks, no food for me"? I hardly ever eat onboard aeroplanes, and I've yet to meet a cabin crew member who tried to force feed me. They'll be happy as Larry not having to serve you, as it reduces their workload.
In short, just say "no thanks" and you'll be fine.
As for choosing First in order to get a bed across the pond, that's a bit foolish. As another poster has mentioned you can get flatbeds in J on many airlines.