Besides the fact that she is Irish and wouldn't even have to try to nail the accent, Saoirse Ronan would be perfect for the cool-headed and darkly observant aspiring poet-cum-college-student.
In the book, Frances exhibits a cool detachment from her feelings but acts as a hyper-articulate narrator, which we are quite confident Ronan could do with aplomb.
Emma Mackey as Bobbi
Described as "beautiful and endlessly self-posessed" in the books, Sex Education's Emma Mackey could be potentially great as Frances' best friend Bobbi (Irish accent abilities TBD).
In the novel, Frances also recounts the time Bobbi "got her nose pierced and took up smoking" and how she got "temporarily suspended once for writing 'fuck the patriarchy' on the wall beside a plaster cast of the crucifixion."
At the risk of typecasting Mackey, her ability to play the rebel-with-a-cause could make her just right for the role.
Jamie Dornan as Nick
In the book, Frances and Bobbi find themselves swept up in world of an older married couple, well-to-do journalist Melissa and her actor husband, Nick.
Based on Rooney's descriptions (or rather, Frances') of Nick, he is said to have a "big, handsome face" and "looked like he could comfortably pick Melissa up under one arm and fend of interlopers with another".
Naturally, the first person who came to mind was Irish actor Jamie Dornan, who famously played the BDSM-obsessed billionaire Christian Grey in Fifty Shades of Grey.
Bella Heathcote as Melissa
Orbiting in a world of "wine-soaked dinner party conversation and "casual jaunts to the French Riviera", the cerebral Melissa was difficult to cast, but we believe that Australian actress Bella Heathcote could take on the challenge.
Currently starring in Stan's Bloom, the ethereal star could easily convey the steely coolness Melissa exudes in the novel.