When I had my first op last year there was a whole gang of us ‘waiting to go down’ and we got together to chat to while away the time.
Of course, by 1pm we were all starving having eaten nothing since midnight, and our talk turned to what we would eat that night when we got home(bad move, but the sarnis were coming out by then for the lucky early cases) : Bacon and Egg, Macdonalds, Fish and Chips were the common thoughts.
A little of what you fancy does you good as they say, but apparently there was actually a good scientific reason for our choices - it seems that when you are really hungry, your body craves high fat food.
My hospital ham sandwich at 7 that night (guess who was last down to theatre?) was fantastic!