I echo those saying treat it as a season, not just a day and start low key and build things up. Repeating what you like to make them into traditions but maintaining the fun and spontaneity.Your baby will be too young to remember anything this year or next, so it’s a good opportunity to make sure you and DH get a bit of focus and it isn’t entirely about the DC. The more you all enjoy it, the better it will last.
My favourite traditions are the tree, a family movie with hot chocolate, Stockings, Crackers, a walk or something outdoorsy on Christmas Day, board/card games on the extra days everyone’s off work/school.
We do presents from Santa in the stockings. Under the tree there are presents from all of us to each other, though a lot more for the kids than for DH and me! DH and I took on buying presents for each other from the kids as soon as they were born so that getting presents for their parents became something we mentored them in as they grew. At first trinkets like photos of them on a mug or something. When they were 4ish we got them making stuff. By 8 ish we would take them somewhere with a budget and they could choose stuff. And now they’re teens they do it all themselves and seem to enjoy it. Took more effort to get them to think of each other as much but that seems to have clicked now too. I really enjoyed the time talking with them about what to get their dad in the run up and the hilarity of them trying to keep the surprise when they were 4 ish! Also decorating together is great fun too. Badly made paper chains were a staple for a few years! And we sometimes pick up a new bauble for the tree when they’re in the gift shop somewhere we’ve really enjoyed a day out together.
We tend to have a focus on food, making our own Christmas cake months in advance and “feeding” it whisky every week, making our own christmas pudding with an heirloom sixpence, making chocolates, Yule log, mulled wine, shortbread, spiced nuts, marzipan fruits, etc. But it got a bit much and we’ve cut it back a lot. Still do a turkey (or sometimes goose/turducken/wild boar/etc) with all the trimmings. We buy in more stuff and have tried to focus more on activities and less on food.
I remember my grandmother getting totally stressed out with Christmas dinner when I was little and it marring the day a bit. We avoid that. Don’t build things up too much. It’s all supposed to be fun so if it’s not working we don’t stress and just adapt. Pass round the chocolate and nuts. You’ll have a baby so remembering to be flexible and adapt is the especially important. If you don’t like cooking get in a favourite ready meal or something, even if you want turkey - I have had M&S Christmas meals at my PiL’s, who don’t enjoy cooking but like tradition, which meant they could enjoy the day and still feel like they’d done it all (and it was a very nice meal too).
We moved abroad so only spend time with family some years, but sounds like you are not able to do that anyway and, to be honest, the kids prefer Christmas Day at home without visitors.
We get the kids an annual for bed time on Christmas Eve so they have something to read when they’re too excited to sleep and new PJs - which they have specifically said they love. Your baby will be too young for that, but you could get a new board book to read with her.
And there are lots of things we only do sometimes. I enjoy a Christmas market, but not every year. They get a bit samey. Also a decent Carol concert can be incredible, but I don’t want to go every year. And I always find ice skating festive but, again, not every year. I like the idea of elf on the shelf in some respects, but it’s a lot of pressure to do something new every night, we’ve instead developed a tradition of having a few Christmassy soft toys that, over the course of December, slowly make their appearance in unusual places or doing mischievous things (which is the aspect that appeals to me!). DH has got into ugly Christmas Sweaters, so we do that sometimes too. We have advent calendars for the kids but I wish we didn’t do them every year. Kids say they want them but are kind of bored of them by the second week (loved them when they were 3ish - 8ish, though).
We listen to what the DC like and try and incorporate everyone’s favourites without building up too much so disappointment/anticlimax doesn’t spoil things. That isn’t just for the DC. It’s important for you not to be counting too much on your DC loving the surprises you’ve got them. If you expect them to love the new, hugely expensive Doll’s House and they are keener on the 5 quid torch, don’t stress about it. You can’t force stuff like that. The important thing is to have fun together. Laugh about it in 10 years time.