For me in the UK, it had always seemed that pop is an old-fashioned word for fizzy drinks used in old comic books. ('Jolly good show Freddie! Let's get a bottle of pop, what, what?')
Now we just say the name of the drink - 'Let's get some Sprite.' or simply, 'I want to get something fizzy.'
So, is pop cool? Not, as far as I know, in the state(public) schools of London.