To make my life easier when hosting I've previously bought a ready stuffed turkey crown. I find the crown easier to cook (and carve) than a whole bird and it then also sorts the stuffing element.
I can worry about getting the roast potatoes right and the ready made ones from COOK that come frozen are absolutely excellent. So I have bought those in the past too.
Cook the turkey first and then double wrap it in foil and leave it to rest while you then have the oven free to do the potatoes, parsnips and pigs in blankets. Extra stuffing balls if you fancy them. I'd forget cauliflower cheese and Yorkshire puddings (despite loving them both) if hosting for a large crowd because they're just one more thing to do.
Make some spiced red cabbage any time from now and freeze it then you can microwave from frozen on the day. You can also easily steam sprouts in the microwave.
Buy the pouches of turkey gravy from M&S and just heat it up in a pan.
Buy a pudding. We keep it traditional and just do Christmas pudding and custard because everyone likes it. Turkey sandwiches for dinner if anyone wants them.
Ply everyone with booze and nobody will care anyway!
I never bother with a starter on Christmas Day. There is loads of food anyway. I tend to just put nibbles out.....bowls of crisps and nuts so nobody is going to go hungry. Or buy some trays of those little smoked salmon and cream cheese canapes and get your 6 year old to walk round with them on a tray and "serve" the adults. Our 8 and 6 year olds love doing that at Christmas because it makes them feel special and grown up.
Think about easy food for the other days. I'd focus on having a good selection of cheese, boxes of crackers, grapes, a couple of pates and some part baked baguettes. That's an easy lunch or table of snacks for people to help themselves.
Bacon sandwiches or those frozen pastries you cook in the oven for easy breakfasts.
If you have a slow cooker, do slow cooked gammon in cola because it just looks after itself. Shred it up and serve it in bread rolls on Christmas Eve or Boxing Day.
Get everyone to bring alcohol because that's where the cost of hosting can really add up.