We make the stuffing - DH cooks the sausage meat the day before (approximately 10 minutes after the annual phonecall to DMIL to remind him how to do that!
). I always make the rest of the stuffing from scratch, chopping the onion etc, but it depends whether I have stale bread to crumb, or a bag of breadcrumbs previously made from heels/leftovers in the freezer to use, on whether I need to buy the crumbs (I usually have them).
We peel the roasties on 24th, ready to boil and then toss in hot goose fat before roasting ourselves.
We also generally do the rest of the veg ourselves as well, we spend a couple of hours on the afternoon of 24th prepping these and things for the "platter feast" that is our dinner on 24th (a groaning table of things to graze on, that are mostly not seen too often in our house). If I am feeling energetic, I might boil the giblets for turkey stock for gravy (or I might just take out the stock, or even gravy on a good year!, from the freezer that I have leftover from the turkey breast I roast for Thanksgiving at the end of November).
This year, I have made another batch of mincemeat (I put it together 2 weeks ago, need to check alcohol levels in it in another 2 weeks with a trial tray of pies), and a batch of limoncello is soaking as well.
We always make HM cookies on Christmas Eve for Santa - sometimes completely from scratch on 24th, other times we take out a half batch that I make sure to put in the freezer earlier in December to just slice and bake. It's a simple recipe, but a nice one.
Some years I make chocolate truffles, or (the golden stuff inside of Crunchy bars), or fudge - but not generally all the same year.
I've finally learned how to make proper sausage rolls (using jus-rol puff pastry admittedly!), so I might make a few of those.
And I usually make mulled wine on Boxing Day by raiding the spice cupboard (it involves star anise, cinnamon, cloves, cardomam and peppercorns).