Extensive Reading

Extensive Reading is the best way to get enough input to learn English naturally. I recommend that you read about 100 pages a week. In this way, you can absorb natural English and gradually build up your ability.
There are many, many books in the PUK Library. There are graded readers (books written for students like you), and also books written for young people in the U.K. and other English-speaking countries. The most important thing is to start with very easy books and enjoy reading, and make a habit of reading regularly. Check out some of the books available.