what’s the name of this movie?

this movie is probably British, it’s about a girl whose her teacher is in love with her mother and there is one scene where the teacher asked the girl what did your mom say about me? (i don’t quite remember the question) but the girl answered ironically with: di*k.
there were three sisters live in her neighborhood and as I remember their father is taking care of them, they did a party when their father was out? there was also one kid in the same neighborhood who is autistic (maybe) he was accused of getting one of the three sisters pregnant? but at the end of the movie, he turned out to be innocent. 2010\2015