IPCC coaching or self study?

I've registered for IPCC and I'm also working. I have received permission to leave my office early for the duration of my studies (Thank You Boss).

I would like to know if coaching classes are necessary or can one pass the IPCC exams with self studies as well? I'm based in Mumbai and if I need to go for coaching, can someone recommend a good class for me, around Andheri, Grant Road, Charni Road.

I'm appearing for both the groups of IPCC.