The aspiring actor, 20, who is studying at City and Islington College, appeared in the pilot of PRU on 2 March, which has been commissioned for a full series.
Click here to watch Pia Somersby in PRU.
She told BBC Online how she spent time in care and got into trouble at home before being kicked out of school and spending most of her teenage years in a pupil referral unit.
Pupil referral units provide education for children who cannot go to mainstream school.
Pia, who lives in Hackney, said: “My behaviour wasn’t good but I would say I was actually really misunderstood in school. I just feel like no-one understood me and they all just thought I was a problem but no-one was listening to what I was going through.”
She attended Wac Arts College, which provides alternative education for 14-19s through creative arts and mentoring, before joining CANDI to study an HNC Performing Arts.
Pia landed the role of Belle in the sitcom after spotting a casting call on Instagram and was among 200 people who auditioned for parts.
“I kept feeling like I needed to pinch myself, like, ‘Is this really happening?’,” she said.
“All my life I wanted to be an actress and even though there’s been a lot of setbacks, I’m glad I never gave up pursuing acting because that was my outlet for such a long time.”
Click here to read the full interview on BBC Online.
Tim Chaundy, Curriculum Leader for Performing Arts and Music, said: “This is a fantastic moment for Pia. It is a strange but wonderful irony that she was once a troubled teenager in a pupil referral unit herself but has now been able to use it to her advantage and show herself to be a very talented young actor.”