Studying literature is one of the best, if not the best, ways to learn the English language and to develop a "feel" for it. Once you acquire a rudimentary knowledge of English language constructions, you can then build on them by studying literature at various levels. English literature is also the best way to introduce students to a range of aspects, not only of the English language but also of the English culture.
How many of these British authors do you know?

William Shakespeare

All the world's a stage,
And all the men and women merely players;
They have their exits and their entrances,
And one man in his time plays many parts,
His acts being seven ages.

- As You Like It

Sometimes students wonder why they still have to read Shakespeare in English or literature class. Although we are separated from Shakespeare by four centuries, some things have not changed. William Shakespeare was the most remarkable storyteller that the world has ever known. That's because his plays confront you with complex issues such as racism, the gender differences, display of power and the abuse of power and colonialism.
Also, Shakespeare's writings greatly influenced the entire English language and helped contribute to its standardization, with many Shakespearean words and phrases becoming embedded in modern English.
Check out Shakespeare's Sayings We Use Nowadays.

Sir Arthur Conan Doyle

It is a capital mistake to theorize before you have all the evidence. It biases the judgement.
- A Study in Scarlet

In 1891 Conan Doyle published six Sherlock Holmes stories about a fictional London-based detective known for his observations, knowledge and analysis. The very character of Sherlock Holmes was based on Dr. Joseph Bell, a surgeon and criminal psychologist. It was the first out of 60 stories that Doyle would pen about the famous detective over the course of his writing career. The year after, he was paid £1,000 for the whole Sherlock Holmes series.
According to The NY Times, Sherlock Holmes, with 5 million books printed in Europe and the U.S. every year, is the 3rd most read publication on the planet behind the Bible and the Dictionary.

Agatha Christie

Beddoes: Oh, yes, sir, the Italian person.
Hercule Poirot: Eh, does he speak English?
Beddoes: A kind of English, sir. I think he learnt it in a place called Chicago.
- Murder on the Orient Express

Agatha Christie is best remembered for her 66 detective novels and more than 15 short story collections, as well as for her successful West End plays. She is known throughout the world as the Queen of crime.
Several of her works were made into successful feature films, the most notable being Murder on the Orient Express (1974). This is the story of a murder victim found with multiple stab wounds aboard a luxurious train, with thirteen likely suspects, and an incomparably brilliant detective Hercule Poirot.
According to the Guinness Book of World Records, Christie is the best-selling novelist of all time.

J.K. Rowling

Dark and difficult times lie ahead. Soon we must all face the choice between what is right and what is easy.
- Harry Potter and the Goblet of Fire

Best known as the author of the Harry Potter books that became the fastest-selling book in history. The first Harry Potter book, The Philosopher's Stone, is particularly suited to English language students since it is easy to understand. Additionally, it introduces the engaging characters Rowling is so famous for.
J.K. Rowling is also a former teacher of the English language.

Charles Dickens

It is a pleasant world we live in, sir, a very pleasant world. There are bad people in it, Mr. Richard, but if there were no bad people, there would be no good lawyers.
- The Old Curiosity Shop

Charles Dickens was regarded as the literary colossus of the Victorian period, celebrated for his humour, satire, and keen observation of character and society. He was born in 1812. He was removed from school at an early age and sent to work at a factory earning six shillings a week to help support his family. After he survived London's mean streets, largely self-educated, he possessed the genius to become the greatest writer of his age. Many consider him the spokesman for the poor. Oliver Twist, published in 1838, is one of his best-known and well-loved works.