Commerce graduation would be a good base for studying Law and getting into Corporate Law as a specialisation. You can have your own practice of Corporate Law or may you can join a Law firm too.
Yes, the Three Year LLB course eligibility is minimum a Graduate. Therefore, you have completed BCom or thinking of doing LLB after BCom, then definitely you can do it.
Just ensure that the LLB course is under a Statutory University and the college through which you are thinking of doing it is recognised by Bar Council of India (BCI). Further, let me share that there is no correspondence