I had a duck breast with plum sauce last year but I usually get some sliced cooked turkey (carved from the bone) from Morrison's, warm it in the oven and serve it with all the usual trimmings.
One of the best Christmas Day meals I've had though was in an Asian/North African fusion restaurant (in south London) back in the late-90's. In those days my local pub was charging £35 for Christmas Day lunch (it's £55 now!) but I had a starter, main course, desert (choosing some of the most expensive items on the menu and adding on the usual Indian restaurant extras, such as spiced poppadums) and a couple of glasses of lassi, with bill coming to just £10.80, which they then rounded down to a tenner! I was so impressed that I left a £20 tip!
At other times I've simply not bothered. One Christmas Day, for example, I simply couldn't be bothered to prepare everything for my usual turkey lunch (even though I'd bought everything to do so). I just had a Findus lasagne!