The 51-year-old actress returns as Dr. Jean Milburn in the second season of the acclaimed series, which tells the story of her life with her teenage son Otis. In real life, Gillian shares 25-year-old daughter Piper with her ex Clyde Klotz, as well as sons Oscar, 13, and Felix, 11, with former boyfriend Mark Griffiths.
And because of the often-explicit nature of "Sex Education", Gillian has had to take steps to ensure her younger sons don't see the related content she sometimes posts on social media.
"I've blocked my youngest ones from my Instagram account," she tells British Vogue. "When 'Sex Education' ends, that might change. One is 11 and one is 13, and I'm pretty sure they still haven't seen the show, or if they have they haven't told me."
"With the new season about to launch and the fact that it will be a topic of conversation amongst their peers, you never know."
And as for what's made the programme so successful, Gillian muses: "Nothing like this had ever been done before. It allowed young people to have conversations about things that were viewed as shameful. Those things are part of our everyday lives, but people pretend they don't exist because they bring out too many feelings or reveal too much about ourselves. 'Sex Education' blows all of that wide open."
"I'm not prudish in any way, but there are scenes on the show that I cringe at. It's outrageous and that's what makes it wonderful."
"Sex Education"'s second season premieres on Netflix on January 17, 2020.