Hi aspirant,

Yes candidates are allowed to switch their branches while they complete diploma and join a B tech course. So you can definitely do Computer Science and Engineering even if you have diploma in civil engineering. Now to get admission into a college you would have to apply for the lateral entry program that allows you to direct admission in the second year of the program. Most of the colleges take merit based admission in lateral entry based upon the marks obtained in the diploma while some others conduct the entrance tests so it completely depends upon which college you want to apply for.

Hope it helps!