See the book list for further titles and recommendations.
You will need a grammar book for language analysis: we recommend you buy Swan, Practical English Usage (4th edition, Oxford).
You are also strongly advised to use a learner's dictionary (such as the Oxford Advanced Learner's Dictionary, or the Cambridge Advanced Learner's Dictionary. These can be accessed online, or in book format. Links: CELTA IH blog- click here to go to the blog CELTA IH wiki - click here to go to the wiki
Note that access to the wiki is restricted: you will be sent the link once you have been accepted on the course.