Movie about a teenage girl sent by her dad to an English boarding school that was mothers straighten out?

The movie you're referring to is called "St. Trinian's" (2007). It's about a teenage girl named Annabelle Fritton who is sent to the prestigious St. Trinian's School by her father, a wealthy investment banker, in an attempt to straighten her out. The film follows Annabelle's adventures at the boarding school, as she tries to fit in and navigate the challenges of adolescence.