Christmas party what to wear

[Sparklyhat]

DH started a new job this year, there is a work Christmas party (3 course meal and disco) and the theme is 'Black, White and Diamond"

Any advice on what both of us should wear please?! Will these ideas be okay do you think.
Not used to formal do's. I'm assuming he will need a black suit, white shirt, black tie? Or tie with silver design (for the Diamond aspect), or bow tie?!

Could I wear a black sequin knee length dress, with tights and black Chelsea boots or would that look daft? What about a jacket, black blazer?

For the diamond part, I could get a diamanté head band? (Shoulder length straightened hair)

I mainly just want to dress suitably and blend in. As you can see I'm not used to formal occasions and not a huge budget so I'm looking at Tu for outfits

I was in Sainsbury's yesterday and had to talk myself out of a pair of silver sequin trousers, I have black velvet ones but no party to go to.

I think the dress and tights sound fine. Not sure about the Chelsea boots. They’re quite a daytime look. I’d go with heels of some kind if you can manage heels. If not, some delicate/glitzy flats.

I'm not used to heels at all but I could look for some glittery flats