Plan plan plan. If you get stressed this is such a godsend. Google spreadsheet is your friend. Write it down. This way you have a list of what you need to do so you won't forget the pigs in blankets (guilty as charged - a mortal sin).
Fridge and freezer space is your biggest issue. As is managing your prep time. Don't worry about time. If you are precious about time you intend to serve you add stress. Dinner is served when it's ready and that's good enough.
Prep as much as you can ahead. Use your freezer too if you can. Reheating is much much easier. (I have cauliflower cheese in the freezer already).
Part cook ahead of time where you can.
Par boil your potatoes - if they are dry they roast better than wet potatoes. Lots of people actually recommend doing this the day before precisely for this reason. It cuts your cooking time down loads.
Red cabbage is an easy precook win. It keeps well.
What veg can you cook in the same tray? This is really personal choice and depending on how you intend to flavour. But make your life easier. A tray of roasted root veg can be done ahead as it takes a long time to cook and then shoved in the oven to finish (carrots, parsnips, swede, sweet potato, onions work well for this - not green veg).
If your timings are slightly out, just keep stuff wrapped as it will stay warm (this is where part precooking/ reheating works well as you can juggle oven space a little better as it takes less time and you know everything is cooked).
Pan fry sprouts.
Steaming veg is also another option.