It's turkey...it will dry out without moisture.
I'd wrap it in foil with a tiny bit of water...then place foil packet in a pan of simmering water. 5-10 minutes should do it. This is just off the top of my head...hopefully would work.
Don't heat it up at all. Put it on a hot plate. Assuming you are having gravy as an accompaniment make sure it's very hot and pour lashings of it over the meat. Never understand why people heat up turkey.
I would try, heating it gently on a dinner plate, over a large sauspan of simmering water, place another plate on top. Sprincle a little water on the turkey every so often to keep it moist. Good luck
I've cheated with my Christmas lunch several times before now, buying 'carved from the bone' turkey breast from Morrison's cold meat counter and heating it on Christmas Day. My method for preventing it from drying out has simply been to parcel it up in foil, together with a little butter, and heat it in my oven.