Buffet with no servers

You would need to hire a wait stuff to do this

Many couples use disposable plates from Costco that guests toss in the trash themselves. If you rent real china , then you need to hire event staffing from thumbtack.com or Eventective.com

Do you know for sure there won’t be staff? I hired a catering company for a buffet. I thought they would drop food and leave but to my surprise they had two people stay to deal with food!

The only way that you would be able to get away with having no waitstaff would be if your plates and utensils were disposable. But even with disposable items, the trash would probably fill up quickly and I'm not sure who you'd then have handle the trash. Otherwise, you'd need to hire someone to handle cleaning up.

If there isn't wait staff there won't be anyone to do the cleanup after dinner. I would consider hiring people to do that.

Veronica and Jacks make a strong point about breakdown. Most likely your venue contract requires full cleanup or there will be penalties. Don't pressure yourself or your guests to be on garbage duty in their fine attire. The most practical decision is to hire staff to keep the party continually tidy and breakdown at end of night. Also, if you do have them serve, they can portion out food so food doesn't run out in the first round.

I'd ask your caterer and/ or venue coordinator how they typically handle this. They might have staff on hand for clean-up or you might have to handle it from your end.