The party happened yesterday.
The way things turned out, there was a big announcement related to our work literally minutes beforehand, so everyone's attention was on that. I ended up showing up late because I hung around for more info on the big announcement, which I brought to the party. There were a few other latecomers too - it was a weird day for us all.
The pub laid out all the snacks on a side table near our main table and everyone helped themselves. I didn't go near the snacks, of course, that definitely would have been bad etiquette! A waitress served us our drinks and we paid her cash on a drink-by-drink basis, everyone paying for themselves.
I can't comment on the outcomes re: costs and food, etc. It just wasn't possible to get a read on that aspect of things.
So, that's what happened. Nothing worth entering into the Etiquette Hall of Fame.