If you can afford it, buy as much pre-done as possible. I’m a decent cook, pretty well organised and used to cooking for a crowd, but Christmas Day is the one time I take as many shortcuts and easy options as I can. I want to enjoy the day, not spend it juggling pans in a steaming kitchen from the crack of dawn.
I only ever buy a big turkey crown - no faffing about with brining or giblets or wrestling with tinfoil halfway through to stop the breast drying out before the legs are cooked. You can buy them fully prepped, but it’s easy enough to just stick a bit of butter and a few herbs under the skin and some bacon on top. All breast meat, no waste, no leftovers hanging around for days.
I buy pre-made gravy, bread sauce, cranberry sauce, pigs in blankets and trays of stuffing. I do prep all my own veg - roast potatoes, sprouts & chestnuts, parsnips, carrots and red cabbage - but you can get all of that pre-done too, which may be less anxiety inducing if you’re a complete novice.
Then you just need to do a bit of military-style planning: work out all the cooking and resting times and oven temperatures and write a schedule, working backwards from when you want to serve lunch (remember to take the turkey out of the fridge early so it’s at room temp by the time you want to cook it. It can also sit around wrapped in foil for ages once it’s cooked and basted, freeing up oven room for all the other stuff). Literally write the times you’re going to do everything and just follow it.
Also work out where everything’s going to cook (oven/hob/microwave) and what you’re serving it in. Knowing that in advance means you don’t suddenly realise you’ve run out of space.
Doing it like this is still work, but it’s a hell of a lot easier than going full Nigella - and means I can feed a big crowd of people whilst still having fun and a few glasses of wine.
Good luck, OP. And remember, the cook NEVER clears - they get a round of applause and sit on their arse for the rest of the day!