Look for local PUG groups on Steam. I couldn't do tf2lobby without being screwed over by lag, but I found some local PUG groups who send out announcements for when their HL and 6s rounds are about to start.
Mind you, a lot of people in my PUG game were still of solo pubber mentality, and refused to communicate anything useful, only using their mics to berate the team for not meeting their standards. I would assume that actual teams would.. you know.. be coordinated. But if you just want to see what level of play you're against, go for PUGs.