Depends on how heavy you want the meal to be? If you want to actually prepare things, I think a couple of different curries with side dishes is nice.
If you just want the traditional post christmas spread for grazing, AND you don't want to cook, you need to make friends with the pre-prepared counter at Marks or Waitrose. You can buy things like ribs, already marinated, that just need to be shoved in the oven. Ditto with hams or chickens that just get pushed into the oven.
Stuffed jacket potatoes or butternut squashes are lovely, and look good. Also work for any non meat eaters.
Buy par-baked bread that you can then back on the spot to make it lovely and fresh. Have lots of nibblies like olivies and nuts. Definitely splash out on some lovely cheese and leave to the side with crackers and the nice bread. I find people tend to dip in and out of that.
If you want a few hot things that look like you've actually done something - buy a ring of chorizo and fry slices until just crispy, make meatballs and put a pile on the table with some tzaziki.
Obviously, salads etc always good and supplements everything else.