If you can afford it, why on earth not? That's what M&S is for!
I must be a bit weird since despite having hosted more times than I care to remember, I actually enjoy doing it all - making stuffing and pigs in blankets etc., often with carols playing.
Having said that, I never do starters for Christmas dinner, or lots of different veg and side dishes, so it's really no big deal. How anyone manages 5 sorts of veg, mash and roast potatoes, never mind Yorkshire puds as well, I can't imagine.
But I do balk at the idea of cooking the turkey the day before and reheating in gravy! Turkey must come to the table whole, in all its golden glory - the smell of turkey cooking is part of Christmas Day for me - and gravy must be made in the roasting tin, with giblet stock simmered the day before.
We never have Chr. dinner till around 5, so it's never a massive rush, either.