I apologize in advance for the very scant info I have one this movie.
All I think I can remember is that it was English, the protagonists (couple) are heroin users, the woman is trying to raise money to start a business (hair salon?) and at some point in the movie there is a children’s choir singing the song “Creep”.
I watched the trailers. I don’t think that’s it. The only thing I am sure of is that there is a science where someone ducks into a building and there is a choir singing Creep.
I believe that version on ‘Creep’ was used in the trailers for The Social Network - obviously not the movie you’re thinking of, but I figured I’d throw it out there.