BCA

You can opt for MCA. This will help you to understand the theoretical aspects which you have studied in BCA and will help you in gaining the practical experience as well.

For which branch are you looking in B.Tech? BCA stands for Bachelor of computer application so you will study all about computer so don't worry abut physics but basic maths will be there. If you have only these 2 options then go for BCA.
All the best.

What's your total budget for the course and in which area are you seeking admission?

Minimum 60% in all the subjects.

Admission for BCA in many colleges require mathematics as a compulsory subject but don't worry about it because many colleges don't possess any compulsory subject but yes, if you have taken informatics practices as an elective subject in class 11th and 12th, then you have got the key for admission in majority of the colleges.
I am also a commerce student currently studying in class 12th and I am also too much interested in doing BCA.

Yes, you can. There will not be a problem regarding the course.
Only possible problem: during campus placements, some companies may not hold you eligible for recruitment. But nothing to worry, most companies will consider you for placements.

Robotics is not offered after completing BCA.