We tend to dress nicely but not formally - DH wears a shirt and tie but not a jacket (or a more casual blazer rather than suit).
I have a couple of options - I wear Christmas jumpers with jeans on other days rather than Christmas Day itself.
I have a navy woolen dress from M&S that I couldn't wear last year ("too dark") which is just below knee length and has a slight swing to the skirt - which I would wear with plain navy heels most likely.
I have a red tunic to wear over black leggings and boots.
I have another navy dress (Monsoon) which is lighter fabric with bright flowers over it, again needs the navy heels. But only if the weather is balmy like last year - too fine to wear thermal layers under it.
I have quite a few other options I could pull out, I will decide closer to the time. But comfortable and semi-dressy will be the aim. Hair done nicely (complete with my bright red streaks for Christmas!), and makeup on.
DD will wear something resembling regular clothes and NOT a tracksuit. I am hoping to move past sports leggings into either nice leggings and a top, or jeans and a top. I know it won't be anything resembling a skirt or dress. She will possibly accept me putting her hair in a plait to make it look nice. (She'll be 11).