You can reheat turkey.
This is from the NHS website.
Keep cooked meat and poultry in the fridge. If they are left out at room temperature, bacteria that causes food poisoning can grow and multiply.
After you've feasted on the turkey, cool any leftovers as quickly as possible (within one or two hours), cover them and put them in the fridge. Ideally, try to use up leftovers within 48 hours.
When you're serving cold turkey, take out only as much as you're going to use and put the rest back in the fridge. Don't leave a plate of turkey or cold meats out all day, for example, on a buffet.
If you're reheating leftover turkey or other food, always make sure it's steaming hot all the way through before you eat it. Don't reheat more than once. Ideally, use leftovers within 48 hours.
My suggestion would be, and this is what they do in restaurants, is to slice the turkey and put in an oven proof dish. Cover with gravy and then cover the dish with tinfoil. Heat in the oven until hot.
As long as its hot then you will be fine. If unsure then give it a blast in the microwave before serving.
Honeyb
x