Lots of good advice here - especially 'it's just putting things in and taking them out' - don't stress yourself out! If you've ever cooked a full English or any meal with quite a few different timings in, it's exactly like that, but you can do loads of prep beforehand to make it easier and actually it's quite slow moving because the turkey takes ages so you have plenty of time to prep.
Get a turkey (or turkey crown if there's not many of you). Work out the cooking time of that, add an hour or so on for resting (up to 2 hours, if you've only got a small oven and need time for everything else).
Working back from that, work out when your potatoes and veg need to go in.
Buy pre-made stuffing mix and some fancy pre-made gravy if you like. Ditto pre-made pigs in blankets. If you can prep the day before, peel your potatoes/veg and stick em in cold water in a bowl in the fridge, and pre-make your yorkshire pudding mix (always seems better when it's been left to sit overnight anyway, I think).
Day of, throw your turkey in and lay the rest out ready to go - stick your carrots and parnsips in a tray to honey roast or whatever, make your stuffing mix up, get your yorkshire mix out of the fridge after a while so it comes to room temp.
Just before your turkey comes out, stick a muffin or yorkshires tin in the oven with some oil in to get really hot and a deeper tray with fat of some kind, for the roast poatoes. Once the turkey's out wrap it in foil and a teatowel and leave the oven on, then when you're ready chuck your roast potatoes, yorkshires, pigs in blankets and veg in and while they're cooking, do any veg you're doing on the burners (I like shredded sprouts cooked in bacon fat with little crunchy bits of bacon). Not long before it's all ready, heat your premade gravy and throw in some of the juices from the turkey. Done!
OR - and I considered this this year - buy one of the Booths/M&S/Waitrose/whatever Christmas dinners. Much less faff haha.