As Solar said - there will already be way too much food so don't frett about bringing stuff, especially if you have a long drive.
It will go on from 11am - 4pm and people can come and go as they please, I'll be there all the time but I imagine all the best food will be cooked and eaten by 2pm. By then I'm hoping to be sitting back with a couple of cold cans of beer.
I love the idea of using the metal trays as mini ovens by the way. I'll have to see if I can get some.