Harlot's definitely a cheese board if available, if not a coffee (decaf?) with cream is perfectly acceptable.
This is the societal expectation that there must always be dessert (sugar) on a night out for dinner. What did BIWI call it...SOS? Something like that. Can't remember, but it was clever.
It's simply not necessary.
I've never been a dessert eater, or cakes with tea, or sweeties, or whatever. Sure, I like them. They taste nice. But I'd much rather have the cheese or a savoury starter than dessert.
People generally don't care about someone's food choices unless they're
a) worried about the other person, e.g. anorexia/obesity
b) over-invested/have own issues, e.g. if I'm eating sugar/breaking my diet I want to take everyone down with me, or
c) revolted, e.g., I dunno, someone ordering bananas with liver or something 
Honestly, most people don't care. If anyone asks and you don't want to discuss LCHF just say, "I fancy this tonight instead" or something equally noncommittal.
Enjoy your dinner, and congrats on your first week.