Well, it is not necessary to undergo coaching classes, but it is a useful little thing. If u r doing fine at school then there is no need to drop out( from my experience, such coaching classes do help in school studies; especially in solving numericals). Anyway u r in ur 11th std. I would suggest that u continue with ur coaching classes. When u come into 12th and u still find coaching irksome, then u could seriously consider dropping it.

        As for the books, INTERACTIVE PHYSICS is very good for getting ur concepts right. DC Pandey and HCV have lots of sums. In chem, RC Mukherjee is a must. Arihant Organic is also very good. Arihant, ML Khanna, Loney, etc. are good for maths. 

 

PS :Plz donot refer to anyone in the "COMMUNITY" as SIR. It is a  bit embarrassing. 

 

Cheers.