I think I must have been asleep during grammar lessons at school.
Either the same thing here, or more likely, there weren't any grammar lessons at school.
the instrumental case, that's probably one of the easiest!
I'm happy with my old book that was never designed to go with a CD, audio cassette, 78RPM shellac disc or wax cylinder. That, along with speaking to a variety of people ranging from workmates, a lady friend, her kids, people from PF (especially making silly comments on facebook), and subjecting myself to a bit of Polish TV, seem to be quite good ways of attacking Polish from all sides.