Cook the potatoes [boil] with any veg that you have. Carrots, sprouts, cauli, broc etc etc etc - whatever is to hand.
Pile it in layers with the turkey in a casserole dish, so a layer of veg, then turkey then veg etc. Top off with cream and some grated cheese. Put in the oven until the cheese melts and cooks and then serve.
I'd peel and finely slice the spuds, layer in a dish with a sprinkle of salt and pepper and bit of garlic between each layer. Thin the cream with a bit of milk and bung in the oven for a Cpl of hours. (potato dauphinoise). Serve with cold turkey and salad.
Any turkey leftover can we wrapped and put in the freezer and used whenever - curried with an onion, some gravy, creme fraiche. Or finely chopped small onion genylt sauted, add turkey and sliced mushrooms, then pour over turkey or poultry gravy and the remnants of the cranberry if you have any. Serve with mash and a green veg.