Buy gammon joint, boil for time specified minus last 30 mins, today or tmrw. Boil with 10 peppercorns, 1 x celery stick, 3 x garlic cloves, quartered onion (skin on, important, better colour, more nutrients), 2 x carrot ( unpeeled, snapped, don't bother chopping). No cola of shredding, just juicy gammon .
Today/Tmrw. Cool, cut off rind, (give to the birds, they need it), leave thin layer of fat, score in diagonal diamond fashion. Baste with honey, push whole cloves in where diagonal score marks meet so get a matrix/ lattice effect.
Xmas day, follow turkey instruction, take out turkey to rest, increase heat, stick in potatoes 45 mins before eating time, stick in sausages wrapped in bacon and glazed ham 30 mins before eating time.
Get veg on 20 mins to go, make gravy, veg off after 10 mins, then sitting in steamer. 15 mins to go sausages out of the oven, cover in foil and tea towel, 10 mins to go, turn off oven, 0 mins ham out, gravy on simmer.
Meat carved first, then pots, then veg, last the gravy ( as it heats up any issues you may have had with timing).
You'll be fine