This study guide for the CISSP exam (Certified Information Systems Security Professional) is also well suited as a general text book for information security.
There is no hurry to buy the book before the semester starts. The lecture notes and other learning material are sufficient for starting to study this course. The book can be useful to get a deeper understanding of the topics taught in this course. Check Detailed reading for a list of recommended pages for each lecture.
The book can be bought from e.g. Akademika, Amazon.com or from the publisher McGrawHill.