Ofcourse you can go with your academic activities along with NCC activities

You can see NCC Colleges in Kerala (https://coursesinkerala.in/ncc-colleges-in-kerala-2021/) here

hi....

You can join NCC after class 10 , the college or school in which you get admission should have NCC Unit in which you can join . Otherwise, If your school doesn't have NCC unit and you are really inspired to join NCC then you can join it by open cadet entry by contacting to your nearest NCC Headquarter.