The 23rd is usually a hectic day, especially this year as the school term doesn't finish until the 22nd! I cook some kind of casserole in the slow cooker, beef and chestnuts with red wine or similar.
On Christmas Eve I always cook a ham, usually with a ginger glaze. We have braised red cabbage and baked potatoes with it, and mince pies for pudding (not forgetting to leave one for Sion Corn!). We always have mulled wine afterwards.
Christmas Day breakfast always involves something sparkling to drink! I have made scrambled eggs with smoked salmon in previous years, but TBH it is a bit too much when we are going to have a big lunch. So we tend to either have croissants and fruit or something similar.
Lunch is pretty standard. If we are at our house we don't have supper, just a pot of tea and some christmas cake and mince pies is usually enough. If we are at my PIL's though they pull out a whole meal again and everyone groans!
Boxing Day is a buffet of leftover turkey and ham with cheese, pate, pork pie etc etc and always a trifle.
Then I use up the last of the meat in a turkey and ham pie on the 27th.