My Week with Marilyn is a 2011 film directed by Simon Curtis and starring Michelle Williams, Eddie Redmayne and Kenneth Branagh.
This is the storyline IMDB offers:
Sir Laurence Olivier is making a movie in London. Young Colin Clark, an eager film student, wants to be involved and he navigates himself a job on the set. When film star Marilyn Monroe arrives for the start of shooting, all of London is excited to see the blonde bombshell, while Olivier is struggling to meet her many demands and acting ineptness, and Colin is intrigued by her. Colin's intrigue is met when Marilyn invites him into her inner world where she struggles with her fame, her beauty and her desire to be a great actress.
You can watch the trailer below and read the transcript here if you want to understand everything.