On christmas eve we don't really have a main meal as such, we usually have a buffet with lots of snacks and finger foods. Things like filo prawns, chicken wings, sausage rolls , nachos etc.
When I was little we always roasted a ham on christmas eve and had it on homemade christmas bread. So I sometimes roast a ham now too.
Ofcourse , it wouldn't be christmas eve without a few sweet treats too like fruit cake, cinnamon and vanilla cookies, marshmallows etc. We also like to have warm mulled wine or spiced rum.