Actress Carey Mulligan has revealed that she used to spend months preparing for roles because she felt the need to justify her casting, as she had never gone to acting school.

"I didn't go to drama school, I kind of felt like a chancer, so I figured that I had to do loads of home work so that I was allowed to be here. The reality of my life now is that I have two kids under the age of five, and I'm lucky if I can learn my lines and show up," Mulligan said, in an interview to Harper's Bazaar, contactmusic.com reported.

The 35-year-old actress thinks there has been a shift in focus since she began her career.

"We are finally understanding that audiences want to see stories about women who aren't necessarily always nice. You still root for them, you still care about them -- it's brilliantly done in 'Fleabag', and brilliantly done in 'I May Destroy You'. Some of the stuff that both of those characters do is totally morally questionable and unpleasant, but you're 100 per cent behind them, the whole way through. It's really fun to see people behaving badly... I certainly didn't feel any of this kind of activity for the first decade I was working," she said.

The actress also admitted that she was hesitant when she was first offered the role of the vengeful Cassie in the dark comedy thriller "Promising Young Women".

She said: "When the script came to my agent I just didn't know what to do with it. I thought, 'Why would (director) Emerald (Fennell) ask me to do this?"

That changed when she read the script. "I said, 'Em, I just have to tell you, I love it so much, please let's do this.' And from then on, it was just super fun," she recalled.