[boothling]

The Harmer book is pretty much the CELTA course on paper. Along with "Learning Teaching" by John Scrivener, it will tell you everything the tutors will tell you on the course.

If you get good tutors they'll bring it off the page and you'll be able to appreciate how various teaching methods work. Some grammar knowledge would definitely help before beginning the Celta, but I managed to pass so it can't be essential.

I have some reservations about aspects of the course I recently completed, but it seems to be based on sound principles and it at least gave me the confidence to get a job.