But I'd fry some onions, make a white sauce, then chuck in some chopped up ham, and the cooked turkey, also chopped up. Add some seasoning, and you can also add some left over veg if you have any - leeks are nice. If not, add some frozen peas or a tin of corn. Or just have the veg on the side when you eat the pie.
You can either buy pastry - flaky is nice, or make some short crust (half fat to flour). Roll out and cut to fit the bottom of your pie dish, and bake blind for about 10 mins. Then add the filling, add the top layer of pastry, and carry on baking until pastry is cooked.
You'd be able to make in advance and re-heat if you prefer.
DDs also occasionally take some in lunch box and eat cold.