Civil Engineering

You may pursue the B.Tech Part time regular course if available near you. B.Tech lateral courses are not suitable because of working professional, however if B.Tech lateral evening course is available than can be pursue. The AMIE is the another best option.

You can go for top colleges like BMS College of engineering and RV college of engineering.

Demand for civil engineers will increase with growing infrastructure, so the scope is good for civil engineering.

You have not written about the category and home state you belong to. However, under other state quota and for the general category you can get the following NITs and Colleges.
1. NIT Sikkim
2. PEC Chandigarh
3. NIT Manipur.

The ranks below 300 for a general category can be safe for getting admission in government colleges in Civil Engineering.

Your expected JEE Main AIR is about 48373. The last year closing ranks in asked NITs in your category for neutral gender in civil engineering under OS and HS quotas are given below.
1. SVNIT : (HS 84751 and OS 34478)
2. VNNIT : (HS 39678 and OS 32268)
So from above for other state quota (OS) your JEE Main percentile should be above 97 while for home state quota (HS) your JEE Main percentile is enough if belongs to Gujarat.

The eligibility criteria and admission details related to BCA of Symbiosis Institute of Computer Studies and Research, Pune are given below.
Eligibility criteria : Student passing XII from any stream or equivalent government approved diploma in Engineering/Technology with minimum 50% marks (45% for SC/ST candidates)
SELECTION PROCEDURE : Symbiosis Entrance Test Score, Personal Interaction and Writing Ability Test (PI-WAT)
So from above you are eligible. If you have completed you Engineering Diploma with minimum 50% of marks.