Suggest as follows to study / read / review - I wrote them last year, passed all 3 the first round:
1. Aerocourse Ground school - ATP workbook, ATPL questions and answers workbook and Instrument Questions and Answers Workbook
2. Read latest AIM
3. Download Dauntless INRAT Theory App from App store - once off payment - well worth it.
4. Browse through CARS online.
5. Purchase the pdf CAP and CFS from NAVCANADA website
6. Purchase a
www.nizus.com membership for 3 months for all 3 - it has loads of practise exams which are similar to what you will get in the exams - these were great leading up to the exams to keep practising and they give you great explanations of your errors
This pulled me through with all marks in high 80's
PM for more info if you want.