Perhaps you'll meet this person on your course!
CELTA/TEFL courses
I have found the following books very helpful both during and post CELTA:
Raymond Murphy - English Grammar in Use,
Michael Swan - Practical English Usage (There's another good book, but I can't remember the name or author right now)
Jim Scrivener - Learning Teaching
Don't worry about buying all the books beforehand, as your institution should have copies of the good ones.
Then for your post-CELTA life, you can treat yourself to the ones you found most helpful
CELTA is a great course and hopefully you'll have some great tutors, who'll make a real impression on your teaching life.
Good luck and enjoy.