The school will expect you to have what the school has recommended you get. By all means buy other stuff if you want to read more - I bought and read this book:
during my PPL course (I wasn't prepared to accept some of the monkey-see-monkey-do this-is-how-you-tick-the-right-box-in-the-exam explanations about how things worked) but in no way was it necessary to pass the exams.