Worth noting that 'atheism' as some sort of online culture was a response to the US's overt (and continued) in-group religiousity. Europe has secularised rapidly, but without the same response from those who are non-religious/atheist.
Is this any less true of Britain than of the rest of Europe? Asking because several of the leading atheism-as-a-culture figures are/were British and seem to be prominent in Britain as well as in the US.
True, but they weren't noted for it especially say Dawkins and Hitchens. They just crossed the Atlantic and took the easy money to face off against the Lane Craig's and D'Souza's at college show downs. Note the UK doesn't have a stage for, or equivalents to the latter either. The US packages atheism as a consumer product in the same way you do religion and 'muh free speech'. It shouldn't be too surprising.