The accounts module is good for understanding, and compilations should suffice for practice. D.S Rawat's book on accounting standards is really good, and reading all standards printed at the end of the module would improve your language.
For Costing FM P.C Tulsian's books have no comparison. Plan wisely as to finish the whole CAFM in like 4 months so you have the rest one month to re-read and do not ignore theory for this paper.
Since you have so much time in hand, i'd suggest you read the module for The Companies Act, along with Munish Bhandari's book for other smaller acts and the practice manual is an excellent read, for all acts. And it would be criminal to ignore the super scoring Ethics and communication.
For Tax, I personally prefer T.N.Manoharan, but Singhania is a good book too.
And Finally, merely having good refrence books isn't enough. You've got to plan and practice. Law and Tax need constant reading, revision and application. Same for accounting standards.
Costing FM is a scoring subject if you get the knack, and it isn't really that difficult if you practice.
Concentrate on past paper problems and use compilations as often as possible.
6 months would suffice excellently if you plan it all really well, and stick to your plans.
GodSpeed for the hardwork,