If they're willing to do it on their own for themselves - that's on them. You are legally entitled to a 30 minute duty free lunch. If you are not a member of TCTA or similar, please join it now.

Yes, personally I have my lunch interrupted by letting kids practice in the band hall, answering questions, etc. That being said, that's my choice in a small school to just try to make some things work. If they're combative about not giving you that lunch, it's time to talk to an admin if speaking with them directly doesn't work.

It is illegal to require you to work like that, though.