Make lists. Lots of lists.
Buy as much as you can now. So stuff like cranberry sauce, cheese biscuits, pickles. And keep them in a cupboard away from other stuff.
If you are doing a turkey go for a crown. Easier to cook and carve. I always get boneless. And when I do a big meal with 2 types of meat I do a gammon with the turkey and cook the gammon the night before.
Prep as much as possible before the day. So I peel all my veg, make my gravy (jamie oliver does an easy one using chicken wings) and stuffing if I am making it myself. And make my piggies in blankets ready to cook.
Remember that no one will particularly care if you buy ready made stuff. Big time savers are M and S Christmas gravy, ready made stuffing and piggies in blankets. I found no difference quality wise between Aldi, Tesco and M and S last year!
And party/buffet food was the same. In fact Aldi was probably the winner for most stuff and much, much cheaper.
If you have guests staying overnight Christmas eve then do something simple Christmas eve tea. And Christmas day morning the last thing you want is people milling around in the kitchen. So something simple for breakfast like croissants and fruit and yoghurt with a few cereal options. Or a big batch of bacon butties. Don't do a cooked breakfast!
And get everyone helping. But don't be afraid to kick everyone out of the kitchen either. My family know that the only thing I want someone to do is mash the spuds and keep on top of the washing hope. People opening my oven or being stirry fuckers is banned.
And once the main is eaten that's it I have done. Everyone else washes the pots, tidies up and sorts out whatever pudding they want. I collapse and whimper into my wine!