Personally I have found that people who cant speak English dont speak unless needed. Thats why you never learn. E.g. When two people of the same community meet 95% of the time regional language is spoken rather than English. Its also a myth that people who go to a English medium school speak English fluently. I have got many friends who went to a English medium school but have a pathetic command over English. Surely it could have been worse if the school medium was other than English. In my opinion only when you speak would you learn about your grammatical mistakes. All you need is someone to correct your grammar and for you to speak to many people as possible.