With roast veg you can blanch it all & freeze weeks before, freeze in ziplock bags to save space, it's so easy & can't tell they have been frozen at all.
I'm from a big family so used to hosting masses of people.
With your windows could you open them and drape material over the curtains instead? I post a pic of what i mean, and add fairy lights? They'll look nice over the top of dark material .
Just try to as much as you can in the days before & make sure you do all your presenting wrapping early, not something you want to be doing Christmas Eve when you have so much to do!
Also do your non-perishable shop now, drinks aswell, spread the expense into this month.