It depends upon ur ability to grasp things. But in any case, going to coaching will not bring ur ability down. U will get to know more things and be aware of the current affairs. But join with some good teachers. Some tachers are great inspirers. So going to their classes will itslef motivate you. But its my view only. You can decide based on ur availability of time
Self study is best as auditing you can learn from your articleship experience, so that subject you can ready easily, regarding ITSM this also you can read on your own not a tough subject. Reg. Adv. accountancy also you refer PC Tulsian book, its sufficient to learn easily.