WE did a Thanksgiving for 14 people and literally we did the same as Noseovertail. We bought a frozen one (forget the size but it was big) from Morrisons. We have a raised oven with a separate hob above and we prepared everything so when the turkey came out all the other oven based food went in.
2 Thanksgivings ago, I made a turkey in a microwave-oven. You know the ones you find on main land Europe that are part microwave and actually part oven. We feed like 12 people and it actually was damn good. I consider that one of my crown jewels of cooking accomplishments. :-)