I was trying to think what they would likely cut out in adaptation. It'll probably be a 4 parter like LW, but even so, there's a lot to get in and retain both a sense of the case and the relationship stuff they must know is key.
So yeah, I think the full dinner party will go, although I do think it might be there in some form so that the conflict of Robin getting to the end of her tether with him seeming to take her for granted and him having to so beautifully apologize remains. (Plus Drunk!Strike again, which is so entertaining.)
I will be mightily cheesed off if they dont have some form of Chapter 58, too, given how pivotal it is.
I suspect quite a bit of the visits to Cornwall will be dropped, and I can't see them trying to replicate the journey in the storm. I hope they keep both the botched perfume purchase attempt and the successful one, and I think there's a good chance of that because that'd be a funny moment.
I wonder how much of Morris we'll get too, and I think the other cases might be glancingly referenced, but they won't give them much more than a sentence.
Possible flashbacks would be the easiest way to really give Margot the same sense of reality she has in the novel. And I want to see the Strike/Creed showdown too.