so, it sounds like you didn't start out really on the right foot-
showing up late is never really acceptable- the students who were there a few minutes early- had time to get in their space-and organized certainly do not appreciate having to wait on someone who doesn't care enough to show up on time-
so off to a bad start-
as for not being prepared- did you receive a supply list when you signed up for the class? should have-
if you are going to spend money on classes why not go on time and be prepared? then the class will be much more enjoyable for everyone- including you- and you will learn lots.
some shops do have problems with classes- instructors who are not that great- but if you are going to pay for the class it makes sense to go ready for the class-
then if the instructor doesn't teach you anything you could go to the owner and voice your complaints- when the problem is you- well you have no one to complain to-except maybe your mirror.
you should not give up on taking classes because of this one experience- you should learn something from it - go to classes on time- and prepared-
and perhaps check with others about instructors who is great to learn from- who is ...not so much-