Dairylea do those lunchable packs. They're really expensive though, so just have a quick shifty at the shelf when you're doing the shopping and make them up yourself at home. They have little ritz crackers, cheese lumps and ham all separated, so the kids can eat what they want and pick at it.
Does he like croissants? You could always stick some filling in that and see if it works. Otherwise, I'd go with the party food crew! Nothing wrong with a little mini sausage roll, quiche and nibbles, especially if you're giving him a main meal at the end of the day.