A detriment of living in the big city, I guess. A couple of years ago a camera store that was closing gave me two gallon bottles of glacial acetic acid. I just loaded it my car and headed off. I gave some away, but will still have stop bath for a long time to come.I took it home on the subway and no one would have any idea what it was. If I tried that today I'd get locked up.
As for the ventilation question, I would limit the time behind closed doors to maybe 1/2 hour or so, or whatever a recommended air-change interval might be. For roll film, once it's loaded, the door can be opened, so there should be little worry. For printing it should be enough time to get a few prints into the wash, depending on how many students are working at one time. Once a batch of prints are in the wash the darkroom could stay open until they come out for drying, then start the process again.
This is more or less the way I work in my home darkroom, which isn't currently ventilated.