sausage rolls....little ones... make millions, freeze them and cook from frozen in batches through the day
also little yorkshires filled with slivers of roast beef....buy ready made yorkshires unless you really want something to do with your time, roast a joint of beef sometime between now and then, and make a good thick gravy, slice the beef thinly and freeze it. When the day comes, you can boil the gravy and tip it and the defrosted beef into a slow cooker to keep warm. Every so often reheat a tray of yorkies and just dob a slice of beef in, people will be queuing at the kitchen door!
...we did this at a little bash at my mother's and people were begging to know when the next tray was coming through
Make big quiches and cut them small ...individual ones are faffy and the filling to pastry ratio is never right.
Little cheesy muffins or scones...again they freeze well, and will reheat nicely to become oven fresh.
little onion tartlet things maybe??
Big pile of profiteroles for pudding
Hot rolls....great big joint of something and put someone in charge of carving
A couple of bottles of that rekorderlig cider can be a good base for mulled cider, it is already spiced/vanilla-ed, or Pimms Winter warmer is a favourite of mine, it can be hard to get hold of, but you can use up the summer Pimms with apple juice, slug of brandy, and fruity bits and i dont think many folk would know the difference tbh
If you can bear it a Mocktail bar is fun for children, just a couple of different juices, a couple of heavier concentrates to give you a tequila sunrise type effect, some pink lemonade, fancy ice cubes and sparkly straw and most children are in seventh heaven.
Buy lots of those sturdy foil trays for any canapes to pass around and lots of clear disposable glasses for the Mocktails.