I assume your school has a cafeteria then? Not the case for my school. It seems to be a struggle to get even one hot lunch going. At this point, we might not have anything set up until mid November.
Where is this (generally, obviously), that your kid has the choice of meat substitute any time there's a meat main? Both my kids are vegetarian and of there's a meat main, they are getting sunbutter sandwiches.
This is in MA, though, where we have universal school lunches.