It's a very good choice. You can get prepared for your lateral exam for diploma course in civil engineering. The name of exam VOLCET for west bengal,  bihar polytechnic entrance test ,for state like maharastra admission is based on score in diploma course like that every states have there own addmission . You can also contract the colleges for lateral entry with your iti marks sheets ,Date usually varies from one state to another.

This are some college
JMI New Delhi - Jamia Millia Islamia

Techno India University, Kolkata

Aligarh Muslim University, Aligarh

Aditya Engineering College, Surampalem


Government Polytechnic, Nagpur

Government Polytechnic, Mumbai

Sree Vidyanikethan Engineering College, Tirupati

Sandip University, Nashik

You can go for this colleges contract them .

For more information you can visit here
https://engineering.careers360.com/colleges/list-of-diploma-in-civil-engineering-colleges-in-india

Thank you. I hope this answer helps you.