Hello,
If you do your B.Sc. and B.Ed. in English medium and also fill out your 2nd and 3rd grade teacher exam form in English, then it mostly depends on the subject and the school you’re assigned to after selection.

Even if you studied in an English medium, your posting could be in either an English or Hindi medium government school; it’s usually decided by the education department based on vacancies. But since your background is in English, there’s a good chance you might get placed in an English medium school, especially if you choose English as your teaching subject.

So basically, it’s not fixed; you can get either one, but your English background might give you a little edge for English-medium schools.