Something is troubling Sara Pascoe.

An increasingly familiar face on television after guest-starring in acclaimed satires The Thick Of It and Twenty Twelve and stand-up showcases at Live At the Apollo and Stand Up For The Week, she now finds herself on the panel carousel of programmes like QI and Mock The Week. The niggle is that she benefited from positive discrimination on the latter two. Ever since the BBC's "one female comic per panel show" directive went public, women have risked looking like token bookings.

As a smart, autodidactic student of anthropology, Pascoe is an excellent fit for QI, having previously appeared on its Radio 4 spin-off, The Museum Of Curiosity. Still, she suggests, like a number of acclaimed female comics, that last year, "I only got on because of the quota". She alleges "lots of people wish that it had remained secret ... But Mock The Week didn't do it, so Danny Cohen [director of BBC Television] felt he had to make it public."

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From a perspective of equality, she ventures that it's important to show comedy as "a viable career" for women. Equally though, she hates "representing my gender. If I'm rubbish, that's me that's rubbish, not all women. I don't want to be confirming someone's bias."

Pascoe's flaw, if she enters politics one day as she's hinted, is also what makes her one of the UK's most exciting and distinctive emerging comedians - a pro-active honesty concerning unpalatable truths. Last year, she was horrified to find that her cat mistook the purring of her vibrator for another cat. So, naturally, she told everyone about it. "If your first thought is 'I never want anyone to find out about that', then you have to talk about it on stage," she insists.

"I couldn't have made it up. I couldn't have said it to my boyfriend. I was so embarrassed I couldn't have said it to anyone. But, through a microphone, I can talk about it candidly. Because a crowd often thinks you're lying or exaggerating, I never get uncomfortable talking about it."

Shy and formerly "quite awkward on stage", she used to drink before shows. But ever since doctors told her she'd worn out her adrenal glands and thyroid with nerves, she's far more relaxed.

Rationalising her vibrator "revelation", she suggests that audiences "love you to be a little bit freaky because everyone worries that they're a freak. All of us have interior monologues that are by turns disgusting and absurd, and we filter them and only say those things we think we can get away with. Like when you're kissing someone and suddenly think about your mum. It's something [Mexican-American comedian] Louis CK does so well, tells you all these disgusting things about his inner psyche. It's a higher level of observational comedy."

She is just as open about the jealousy that's plagued her relationships, though sharing it on stage has had more to do with "writing as therapy". She admits "it's a really unattractive quality. It's never nice being the irrational person in a relationship, the one who seems to care more. So it became a coping mechanism; if I can make it funny then it becomes bearable. Other kinds of jealousy too, like being in Edinburgh and being jealous of the award winners. It's something I plumbed the depths of, so I'm not secretly ashamed. I find humour in it now because it's so childish."

Her new Fringe show, Sara Pascoe vs History, is essentially about "having a relationship and living with a man". Though she describes it as "more accessible" then her most recent and increasingly assured hour-long acts, she retains her "ambition" to examine "big ideas but to never leave anyone in the audience out. You don't need to know who Napoleon is to laugh about his love letters."

Exploring relationships through "the baggage we bring to them", she's focusing on the choices she's made and those of her divorced parents. But also "the fact that we've evolved from apes and pair bonding exists to keep babies alive, yet that doesn't fit with the modern world. Lots of marriages fail but we keep trying."

In almost seven years as a comic, Pascoe, 33, has also kept evolving as a performer. Born into a working-class family in Essex, showbusiness was in her blood. Her father Derek was a singer in 1970s pop group Flintlock, her mother his most committed stalker. At 18, their eldest daughter became an actor but struggled to find paid work. Only when a wannabe comedian boyfriend took her to an open mic night, and she realised she could write funnier material than those on stage, did she start taking tentative steps towards her vocation.

"Suddenly, if I could do a new material night after work, it stopped my heart shrivelling while I was temping," she recalls. "So at the beginning, it was more of a survival instinct. For ages, I didn't even realise that comedy could be my career, it was just a hobby that I loved."

Nevertheless, she instantly stood out, reacting against the open spot tendency, especially amongst women, to self-deprecate. Audiences at unpaid gigs "laugh if you're horrible about yourself, maybe out of awkwardness, maybe because they hate you," she reasons. "Or maybe because that's just what they expect from you.

"I would look around an audience, half of them women, and think 'We're pumping sewage out into the world'. Whenever a woman actively says something about her own appearance negatively, she reinforces what we're told by all those magazines we hate … whenever I went on in a dress or a skirt and felt that I looked nice, I could sense the audience thinking 'How dare you?' It wasn't that I was going to start a revolution, I just wasn't going to be part of that."

Instead, Pascoe established a reputation as a quasi-character act, declaring to crowds how wonderful she was. This high-status aloofness worked for a time, a "gateway" to build her confidence. However, by 2012, she had realised she was more passionate conveying ideas as herself, because with a character "you can't connect with an audience in the same way. You can shout at them and do weirder things. But in stand-up it feels like a two-way conversation … it feels so much stronger." Revealing that her loving father had wanted her aborted, "would have felt like a lie, a construct" coming from her old persona. Now though, "there's a sense of truth".

With her mixed experience of BBC reputation management, it's ironic that two of her most high-profile acting roles have been as corporation employees. As Jessica Hynes's "mini-me" publicist, she was cheerily vapid in the BBC's self-flagellating W1A and its predecessor, the Olympics farce Twenty Twelve. Appearing alongside Glasgow's own Doctor Who, Peter Capaldi, in The Thick Of It also proved memorable.

Again, she'd auditioned for a part as a "PR idiot" but instead got the role of Richard Bacon's Radio 5 Live producer. Locked in a rehearsal studio with Capaldi as the "Gorbals Goebbels", spin-doctor Malcolm Tucker, improvising in full, bug-eyed, throbbing temple mode, "screaming in my face", she found that she couldn't stop smiling "because it was so fun. They had to remind me to look sad!"

As she waits to hear if her latest BBC commission, a Radio 4 adaptation of her previous show, Sara Pascoe vs The Truth, is given a series, she's started writing a book, an amalgam of autobiography, feminism and science literature, and a play, potentially for the 2015 Fringe. Ultimately though, she fantasises about performing a run in London's West End by night, so she could study at the London School of Economics by day.

Endearingly, it was performing on Live At The Apollo that confirmed to Pascoe that she was a comedian, that "it could never be taken away from me". But it was her unlikely recruitment to Stand Up For The Week, Channel 4's late-night, topical stand-up programme, that convinced her she could have a future in government.

Creating 15 minutes of new material in two days, five of which made it on screen, was "nerve-wracking, I was completely out of my depth and couldn't walk in my shoes" she says. "But over 16 weeks, I got good at delivering jokes I knew weren't ready, that made my skin crawl because they weren't good enough."

And belatedly she appreciated that "it's just showbusiness. You say it like it's the best punchline ever. A third of them aren't listening and they're laughing because of the rhythm. I thought, 'Oh God, you have so much power!'"

Picturing herself in the House of Commons, she laughs, admonishing herself for "delusions of grandeur" and naivety about a candid stand-up sustaining an unimpeachable reputation. Because - and let the record show this - her boyfriend, comedian John Robins, suddenly takes this opportunity to disrupt our phone chat by dancing before her in his pants.

Sara Pascoe vs History is at Assembly George Square Studios from July 30 until August 25 (not August 11), 8.15pm