The Weight of Water by Sarah Crossan (2012 in Great Britain, and 2013 in the US.)
This is a novel in verse about a girl new to England with her mother, from Poland. Kasienka (often known as Cassie in England) and her mother are there to look for their father and husband. Kasienka’s tata had left them and gone to England some years before. Her mother is desperate to find him. They take a small room in a boarding house, and Kasienka starts going to school. The school head incorrectly assumes that Kasienka needs to being in a lower grade level because English is not her first language. Kasienka eventually takes tests and blows them all away. She is moved up to her proper age group. She navigates the pitfalls and bullying from other girls as she discovers the new life her father is living, a relationship with a boy, and how well she can do on the school swim team.
This is a good read for middle grade kids.