If you can get hold of the Jamie Oliver Xmas DVD you will find it a great help! My husband always does the lunch for us and he says that this DVD was invaluable - lots of handy hints and time saving ideas. Our lunch was amazing last year so I can highly recommend it. The DVD should be pretty cheap as it came out about 2 years ago. I prefer our Turkey to be cooked on Xmas Day as otherwise it can be a bit dry. Another trick is to roast it up-side down for 75-80% of the cooking time...this way, all the juices run to the breast meat! I would never stuff the cavity of a large turkey, only the neck...cook stuffing seperately.
I would also recommend that you sit down a week before the event and write yourself a schedule, including all the jobs you can do on Xmas Eve. Everything from what time you need to peel the carrots to when you will lay the table, when to put the spuds in, etc, etc. It really does help..it takes a bit of time to formulate, but I always do it for dinner parties as it really helps to keep things organised and reduces my stress levels. I always peel the veggies the day before and leave them in a cool place, in cold water. Its all in the planning! The very best of luck!