"It's just so good and so refreshing and so different to anything I'd ever seen before," 24-year-old star Rooney said of Tom Bidwell's adaptation. "It was just so good to know I could audition for something and not have to change. I could audition as I am - how I look like - and I didn't have to change."
My Mad Fat Diary follows the spirited but troubled Rae as she struggles to adjust to life with her friends after a summer spent inside a psychiatric hospital. But did Rooney feel any pressure bringing a real-world figure and her issues to life? She insists not: "The real Rae said to me the day before filming, 'Don't make this about me - don't worry about making this [character] who you think I am, take anything that you've experienced and just make it real,'."
Rooney's Rae loves music and has a genuine lust for life - set in 1996, My Mad Fat Diary boasts a soundtrack that takes in the best of the Madchester and Britpop scenes. But a familiarity with the show's tunes was practically the only link that Rooney's co-star Nico Mirallegro - who plays handsome but moody Finn - had to the time period...
"I was five in 1996!" Mirallegro laughed. "I'm quite familiar with all of the music in the scripts, but with regards to what I was doing in 1995, I've got no idea. Watching [Manchester] United win the League probably!"
The former Hollyoaks and Upstairs Downstairs star explained that his character Finn is "quite moody and down" until he recognises a possible kindred spirit in Rae.
"When Rae comes in and he sees this figure who is so similar to him, I don't think he likes the fact that this new person has come into the gang and that she's got her own ways about her," explained Mirallegro. "Then suddenly it clicks into place [for him] that they are more similar than they thought and that's what brings them together."
And speaking of similarities, another of Mad Fat Diary's stars - Dan Cohen, who plays Archie - admitted that much of what the show's characters go through across the show's six episodes is "not dissimilar" from what he experienced throughout his own teenage years.
"All of the characters have something that they're keeping to themselves - that they're hiding or struggling with - and all of the characters to some degree think that their problems must be the worst," Cohen said. "They're sure that they're dealing with the most horrible things and that nobody will understand them.
"I definitely remember feeling that at certain points in my teenage years… and not realising that probably everybody else had the same kind of feelings."
Series lead Rooney added that she hopes My Mad Fat Diary will help teenage viewers to come to terms with their own issues, particularly those who may be suffering from mental health problems.
"For me, I think it's about time that it was brought into the mainstream," she said. "Because there's such a big taboo about it, no one speaks about it. How can you expect a teenager to admit that they're struggling if no-one talks about it?
"We talk about everything else that's supposed to be taboo - there's loads of programmes about sexually transmitted diseases and that kind of stuff… this is just as important. I think it's good that it is being brought to people's attention."
My Mad Fat Diary begins on Monday, January 14 at 10pm on E4.