Learning English in a non English speaking foreign country can be very difficult. Many students in Asia and non English speaking parts of Europe often have challenges when they try to learn English at university.
A key to learning English effectively is immersion in an English speaking country. That is why studying English at top UK universities can be a very helpful option. One of the major reasons for this is that English is the primary language of the United Kingdom, particularly in London and other parts of England. The English language actually originated from the UK, so there are plenty of available resources such as books, movies and songs in the English language. There are also many English speaking people to meet and become friends with, which will instantly propel the student's language skills.
When choosing a UK university to study English, it can be useful to get the Good Uni Guide 2012 which gives details about the top UK universities.