So, we aren't doing Xmas dinner on the 25th - we have one on the 23rd with DH's older children, and another with my relatives on the 26th.
So we decided that as Xmas day is just us and our young kids, and the day is more about playing games and watching telly, we would have a big, late cooked breakfast and then just have a snacky buffet thing throughout the day.
No idea what to cook though! Preferably stuff that can be done the day before. And it mostly (not necessarily all) needs to be gluten free for DH. We don't have much budget either 
So far I've thought of:
Chicken wings with glaze
My famous cheese dip with crudités
Breadsticks, crackers etc
Potato salad/coleslaw
...?