As a Brit, I don't think this is true; I think our country has some really great and unique culture. The history of Britain was built on blood and as such there is a lot of conflict and violent crimes occurring here in the street. This is one of the biggest problems of the country, knife crime specifically, and a large number of our population have been led to believe that the knife crime and violence is a new thing that is the result of immigration which is a perception designed to keep people all hating each other through fear and racism. (all of this could perhaps be saved for another thread titled "What is wrong with your country?" , but more on that later)
Aside from this, Britain has some of the most amazing countryside I've ever seen, along with some of the most polite and friendly residents. If you're more of a city/town person, we have some incredible architecture dating back to historic times and being around those buildings really does make you reflect on the scale of life and how long its been going for. Along with the places, we have a bunch of native crops and foods that you don't find in other places such as full English breakfast and some of the really hearty stews and soups that are more common in winter time. One last piece of British culture that I'm the most proud of is the music. If you look at a list of British musicians and bands you'd be amazed at how many of the musical geniuses that have blessed humanity that are British. To just name a few, Queen, Black Sabbath, Led Zeppelin, Beetles, Pink Floyd, Amy Winehouse, The Rolling Stones, The Stone Roses, Radiohead, etc etc etc etc And the lively street music scene you can find up and down the UK.
Lastly, one last part of British culture that is widely important to many many people is how "multicultural" it is here and how all walks of life are accepted and welcomed by most (apart from the moronic racists). There are places of worship up and down Britain for all religions and a lot of foods for people with dietary requirements from their religion can be found in all of the main stores as well.