Dear Arpit, please try joining English spoken classes after your 12th exams. After your 12th exams and your B.Tech admission, there will be few months for you. Try joining a Spoken English coaching centre. From now every day, try learning atleast one new word in English and try to use that in a sentence. At the end of the week, try using all the new words and try framing a paragraph. Then you can always follow the golden rule of learning English- read news papers. Try watching English movies, web series, sitcoms, documentaries in English. You will start slowly getting a grip on the language and by the time you actually join an Engineering college, you will be ready.
Hey there
It's true that state board students face problems when they move to colleges for professional courses which are taught in English. See do not take it as your only problem lakhs of students get this problem as many students from state board go for engineering. I'll advise you to learn English though not much English is required it's not like you should have Shakespeare's English. Students from English medium in engineering have weak English so do not be panic you'll slowly manage.
Good luck
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