See its always better for a student to pursue what is his/her passion. Now the idea you are saying about coding along with your course then you can do it but I would say that you will not be mentally satisfied because when you will learn about the Chemical/Civil you not find the essence of CSE or IT in it and as a result you can lose interest in studying. So I would say you should go for other college for CSE or IT. See in JU also in placements the core fields get the average packages which are not that much as compared to CSE grads in JU. So even if you get a  CSE genre job, you will not be paid the same as the CSE grads. Now the average salary you will get studying in JU with some random course will be equal or less than equal packages in other colleges where you get CSE/IT. As a result as per my opinion I would recommend you to go for CSE/IT.

I hope this answer helps. All the very best for your future endeavors!