I don't know about drinking at KC meetings. I've never been to a KC meeting. But on my graduation night I was partying with some Italian Catholics and we ran out of booze. They called a KC official and he opened up the KC Hall "stash" and it was like a liquor store. I don't say that to poke them. I don't care if they drink. Or when they drink. I certainly don't judge them for that. But the preponderance of evidence from my eyewitness experience suggests they do some drinking there, whether before, during or after their meeting I don't know (or care).
If i does not go on at the formal meetings, it certainly does at the informal "meetings" at KoC halls. Then you have the White Horse Inn which i know little about.