I'd second the French 75 for cocktails - easy for a group and festive. You might also have a G&T / V&T option on hand (but make them singles!). If you have any non drinkers then seedlip do decent gin-ish subs. Sparkling elderflower for kids.
Gougeres - basically cheese profiteroles - I love with drinks before C'mas dinner. I have an old Clare McDonald recipe, but the Felicity Cloake one below will be good (they freeze amazingly well so you can do them in advance). You could just have those with olives and some salted and smoked nuts, but if you have a real crowd you could add crostini and older kids can help make them. If you want a proper sit down first course I'd go for a walnut and blue cheese salad w bitter leaves - but light on the walnuts and cheese, you need to leave space for roasties
For the evening we are very cheese board centric - sharp cheddar, a goats cheese, a Wilton and a milder Italian blue, plus charcuterie - salami and parma ham, plus olives, antipasti, some winter salad (buy it) for those that want it, celery. Humous and a butter bean (or something) dip if you have veggies. Little russet apples. Crackers various - Peters Yard sourdough, and some with seeds. Port and/or sherry is really nice to offer here.
I don't think you need to go anywhere near quiches etc - no one will have room and you will be exhausted. If you really think you need more then smoked salmon (or trout is cheaper) with lemon wedges and Irish wheaten bread. Obviously people can get cold Turkey etc if they want do, but we tend to do the cold cuts with fresh roasties and winter salad on Boxing Day.
For pudding, have some nice chocs and some tangerines. There will be cake and mince pies anyway.
https://www.theguardian.com/food/2019/dec/18/how-make-perfect-gougeres-cheese-puffs-felicity-cloake-recipe