Un stable

I've just got back from the local Junior School's Carol Service, in the church next door. I don't have a child there any more but our choir had been asked to sing. It was actually quite a nice service and not too long. The nativity scene was created over the course of the evening, with children bringing up various bits while each carol was sung.
We're about to add a few last items to our Waitrose delivery. How much food do you need to feed 12 people for 3 days??