As one of my friends was a student at IET Lucknow, from her experience I can for sure tell you that it is really hard for you to get admission in most of the colleges with a gap of three years. In addition to that, to get shortlisted for admission at IET Lucknow, you will have to appear in the UPSEE exam and perform really well in it.
I would recommend you to first learn about the procedure of availing a loan, the interest rates, how much to pay, the time after which you will have to start repaying the loan, etc. Having prior knowledge of all these will be better otherwise you might get fooled.
Additionally, keep a valid income certificate with yourself. You can apply for the scholarships provided by the UP government. Most of the IET Lucknow students avail of the scholarship under the state government.