Parboil potatoes in salted water for 8 minutes. Drain, return to pan and shake saucepan with lid on. Spread the potatoes on a baking tray lined with non stick paper and freeze. Once frozen, put into a freezer bag and store. On the day, heat rapeseed oil in a metal roasting pan in the oven until hot. Take hot pan out, put on gentle heat on hob to keep oil hot, and spoon in frozen potatoes, turning them as you go. Roast in the oven for about 55 mins, turning once. No faff at all on the day, and the freezer dries the surface slightly so they are mega crisp.
Prepare and parboil parsnips, and freeze as above. Cook from frozen on the day in oil and maple syrup.
Make these carrots and red onions 2 days ahead www.bbcgoodfood.com/recipes/caramelised-carrots-onions
If you can't be arsed to make your own stuffing, buy a packet. Chop a red onion finely, and cook slowly in loads of butter. Make up the stuffing mix, and add the onions and butter. Sling in some cranberries and chestnuts, then freeze it either in a foil tray, or in balls. Defrost on the day and cook as normal, brushed with melted butter.
Chop leek into rings, put in a frying pan with butter and a splash of water. Cook until almost done, then cool and heat through when needed.
Bread sauce can be made in advance, freeze, then add the cream and butter when it's thawed and heat through gently.