Leave the Aviation Theory Centre green book well alone - that is a book suited to the theory behind instrument flight, and actually flying the aircraft. It is not in any way an appropriate document to teach you to pass the IREX exam.
Yes, the ATC book covers everything, but it is presented in such a way that leaves you no idea which things are crucial, and which are just supplementary information.
Use Bob Tait, or one of the well known theory instructors around the country, to get you through the exam, and the ATC book for help with the actual instrument flying.
bentleg, with all due respect, the reason you needed so much extra work for the exam was that you were using the wrong textbook. The practise questions in ATC are not at all similar to the ones you'll get in the real exam, whereas in the BT books they prepare you very very well indeed.