After focusing on contemporary British English reads in the past few years, and learning a whole lot of English that I didn’t know existed, I can say that British English is a lot of fun.
If you want to get started on the journey, I recommend from experience two fun books, based on the amount of words and phrases particular to British English that I found in them on my own journey:
and, among the chick lit books, especially Catherine Alliott’s, such as this one:
Catherine Alliott, The Secret Life of Evie Hamilton
Want to have a quick taste of British English? Here you go:
British English Phrases, Idioms, and Expressions (Letters A-C)