Some great advice on here. If you want to stretch the turkey for other meals after Christmas - assume your guests are staying afterwards - eg risotto, chinese style pancakes, asian salad, cold cuts etc then a whole turkey is best.
I think a few meals prepped ahead is OK but sometimes I like escaping to the kitchen to cook to get away from everyone, I find all the company a bit much by Christmas Eve Boxing Day. And there's only so much sitting around I can do, I'm not very good at it. What I do object to is laying the table, clearing away and washing up after every meal - you need to delegate these tasks very clearly either straight off or at the start of each meal.
Re the internet delivery - I also do this, but inevitably there are some missing items, so I normally get the internet shop by 21 Dec and then plan a dash at an odd hour to the local supermarket on 23rd, to include the veg. We also tried running the gauntlet with our turkey last year, leaving it til Christmas Eve as the previous year Waitrose reduced their Norfolk Bronze ones to half price. Typically, this didn't happen last year. Even on Christmas Eve mid afternoon, there were loads of turkeys to be had in the 4 supermarkets DH visited in town at work, so I wouldn't worry about empty shelves.
Totally agree with the theskiinggardener - don't worry about doing everything at the same time, cook the bird first, wrap it in lots of foil and teatowels to keep it warm and then crank up the oven and do everything else. Much less stressful.
One year I made masses ahead, and had about 10 things on the plate incl home made bread sauce, mashed swede, red cabbage, sprouts with bacon, etc etc. Ludicrous - far too much, loads thrown away, this year its just sprouts, carrots, one other veg, roast pots, pigs in blankets and I will buy the bread sauce.