Is it a good idea to pursue Diploma in CS as I want to do lateral entry B.Tech after it?

Yes, it is a very good way to pursue both. Also, you will get two degree, one is of Diploma and other is of B.Tech course, which will increase your experience. But, be attentive while pursuing the B.Tech course, because it is more practical based than the Diploma degree. It might led you to face som

To be eligible to pursue B.Tech CSE, you must have completed 12th standard with mathematics, physics and chemistry subjects or three years Diploma in CSE course from a recognised board. There is a big difference in the attitude of those having regular B.Tech and lateral B.Tech. It generally seems t