Resources, resources...

There are rich resources on the web about dialects of British English. Universal Teacher, for example, presents this extensive guide that defines the term dialect, discusses topics like social functions of dialects and historical changes, as well as exposes some features of traditional dialects.

Some aspects of British English are roughly summarized by this other webpage, which sends us to topics like the Queen's English.

Finally, find yourself immersed in experiencing the "local colours" of different dialects of British English and understand their distinctions from other English varieties.