Cobie Smulders, known for her role in “How I Met Your Mother,” delivers a lively and humorous performance in this British comedy. She stars as Joanne, the frontwoman of The Filthy Dukes, a Britpop band that enjoyed fame in the 1990s. After a night of heavy drinking with her friend Sara, played by Jessica Hynes, Joanne accidentally ends up enrolled in a university. Determined to out-party the young students, she discovers they aren’t as captivated by rock ‘n’ roll as she is. Nonetheless, romance and fresh starts may be in store for the rocker Joanne.