I do most of my prep on Christmas Eve (some on 23rd) rather than frozen.
But you can peel all veg and potatoes on 23rd or 24th. And slice up ready to cook.
Keep potatoes, carrots and sprouts covered in cold water, in separate pots/plastic containers - but change it on 24th to avoid getting slimy.
Onions, garlic, parsnips all need to stay in airtight containers but NOT in water. (And separate!).
Make and freeze breadcrumbs, or even make the stuffing and freeze it.
You can also make herby (& garlicy if desired) butter in advance and store as a log in a greaseproof paper roll in the fridge, or freeze.
Soup for a starter can freeze too, and have some part baked bread rolls to go with it to pop into the oven after the turkey is out shortly before you eat.
You could make the gravy the day before and just add the meat juices and reheat when getting ready to serve.
I know some people do par boil the veg, toss them in their seasonings (and potatoes in goose fat) and freeze those ahead of time so they only need to be roasted on the day. And the same with mince pies, rolled out and filled, ready to just bake or even just reheat when needed.