Code of Canon Law:
Can. 986 §1. All to whom the care of souls has been entrusted in virtue of some function are obliged to make provision so that the confessions of the faithful entrusted to them are heard when they reasonably seek to be heard and that they have the opportunity to approach individual confession on days and at times established for their convenience.
Ordinarily confessions should be offered at regular days/times. However, some areas have severe shortages of priests which makes this either very difficult or near impossible.
My presumption with the schools is that they probably organize penance services with confession a few times a year for the students.
If your parish has a parish council you could discuss the matter with some of the members of the council and see if they are willing to raise the possibility of regular confession times with the pastor.