If you asked any English teacher, what they think is the best ‘authentic’ reading material for you to improve your English, almost all of them would say a newspaper. I would have to agree with them. English newspapers are great. The main reason for this is because newspapers are much more current than textbooks. Textbooks can become outdated rather quickly. The reading material they contain can soon seem old fashioned and boring to the reader. However, newspapers contain up to date news and stories. Plus, you can read a different one every day.
The English language can be very confusing. Especially if you are learning British English. In Britain, we use a lot of slang. Slang is informal words, phrases and expressions that originate from groups of people or different regions. Slang is more common in conversational English than it is in written English. One of the reasons slang is so confusing for English learners is because there are so many variations regionally. For example, slang used in Manchester is very different from slang used in London. Also, the slang commonly used in American English is very different from what you find in British English.