Complicated Father/daughter/stepfather relationship set in England

Hello, I am trying to find a book from the late 90's early 2000's. I thought the tile was "Daddy" but I couldn't find it. Set in England. A teenage girl's parents divorce. Father/mother start new relationships, marry, and have kids with new people. The stepfather Nick seduces his stepdaughter. They think she gets pregnant by Charlie a classmate. Her father ( I think a professor) takes her back in to help her raise the child.