Yeah you can get into NIT by just scoring 30-40 but you'll suffer a lot during your first year as the course syllabus of first year in NIT/IIT includes topics that are taught during JEE preparations and the professors of NIT/IIT are no good. You won't understand a thing in class. You'll have to study by yourself. You'll get into a college by just scoring 30-40 marks, whereas your batchmates will mostly be those who have spent 1-2 years in KOTA and studied from the best faculty in the business. They'll take you to playground,they'll take you to bars and when it'll come to exams, they'll just enjoy and still they'll fetch more marks than you, because they know most of the things that has been taught in the class and you won't have a clue about whats happening.

You want my advice, drop for a year, prepare well for JEE(Advanced){yeah you heard it right} and try to score atleast 70-80 marks. You'll get a very decent branch in one of the top 7 IIT's. As far as JEE(mains) is concerned, if you score 100, you'll definitely be getting into 1 of the top 10 NIT's. And if you want a government job then take admission in core branch in whatever college you get and start preparing for GATE from 2nd year onwards. You can easily get a job in PSU's. The pay is lucrative in PSU's and it's a government job too. Don't think that getting into IIT will get you a better job than PSU because their is no reservation when it comes to campus placements in IITs so you'll have to compete with those candidates who have scored more than 100 marks than you did in JEE so the competition is quite stiff their.