I don't think you need a starter but chicken liver pate is easy to make and can be made ahead.
One starter / canape I've done a few times (not Xmas) soak dried apricots over night, stuff with a bit of brie, wrap in bacon and bake for 10 mins.
Filo parcels with brie and mango chutney are also easy and look impressive.
You could also go retro 1970s and serve a slice of melon, with or without Parma ham.
A rustic 'terrine' can also be done ahead.
You need
Streaky bacon
chicken mini fillets or chunks
2-3 different types of sausage
chicken fillets
Line a loaf tin with the streaky bacon with the ends hanging out.
Skin the sausages.
Put pieces of chicken, chicken liver and mould the sausage into a sort of thick patty.
Keep putting layers in until the tin is full.
fold the over hanging bacon to make it a parcel.
Put in the oven for 30 mins.
THIS IS IMPORTANT
put a plate or small chopping board on top and weight it - there is a lot of fat in the terrine, this will push it out, after about 10 mins, drain the fat off and turn it out on to a plate.
Some slight variations on the usual sides.
I wouldn't do all of these but have done them in the past for dinner parties.
Roast carrots in honey and oil.
Make a mash of potato and parsnip with a clove of garlic and some powdered ginger or nutmeg.
Swede mashed with cream and crispy bacon.
I've also done a parcel of veg, not very Xmassy but could be adapted so a piece of carrot, a baby corn, a green bean tied together with a bit of spring onion - maybe too fiddley for this.
One pudding idea I saw on TV, I think it was James Martin, was to crumble up a Xmas pudding and mix it with vanilla ice cream for a slightly lighter pudding - but don't try to set it on fire.