Whilst there are a great many options for Christmas dinner the good old turkey seems to still be the favourite.
If like me you can never remember how many people a certain sized turkey feeds, nor how long to cook it for, you can't go wrong with BBC Good Food's pages on weight, thawing and cooking times: http://www.bbcgoodfood.com/howto/guide/foolproof-turkey-guide
I don't truss the turkey but I smear it with butter, season and cover it with streaky bacon, covering it loosely then with foil before going into a hot oven (220 degrees fan). After 30 minutes I turn the heat down to 180 degrees (fan) then for the last 30 minutes I remove the bacon and foil to allow the turkey to brown. Once removed from the oven I put it somewhere warm, covered with foil and a clean tea towel until it's time to carve.