‘Thank God,” emails the artist Heather Phillipson after our interview, “art is one environment where it’s OK to be a weirdo.” She’s not just talking about the giant swirl of cherry-topped, fly-infested fake whipped cream she’s poised to install on Trafalgar Square’s fourth plinth in London later this month, but her whole artistic practice.

She explains that she was “partially raised by border collies, the sharpest and most compulsive of breeds”. And like a border collie, Phillipson is incorrigibly digressive. “I follow a material trail like a dog follows a material trail … pausing to sniff butts, urinate, head off in unauthorised directions, and make their own systems.”

In her 2014 installation in New York titled Immediately and for a Short Time Balloons Weapons Too-Tight Clothing Worries of All Kinds, she made just such a system. Each visitor entered a painted shower curtain-cum-orifice into a space decorated with coiled cables, filled laundry bags, raunchily jutting toilet-roll holders, a little bucket suspended by string and swirling paintwork. Then they sat in an inflatable birthing pool with a video screen suspended from a hoist above their head, showing domestic, public and online spaces, and playing a characteristically deadpan voiceover from Phillipson. At one point, she emerged on screen, leaning in as if to give you a soothing facial as you prepared, perhaps, to call the midwife.

‘Whipped sounds propulsive’ … a maquette for Phillipson’s fourth plinth sculpture, The End. Photograph: James O Jenkins

Phillipson revels in shifting our perspectives. What is it like to see yourself as an alien or as a drone sees you? What is it like to attend an exhibition as the spectator only to find yourself pregnant and scrutinised? Her art is a series of mind-altering alienation effects, echoing philosopher Timothy Morton’s project of queering the “patriarchal, hierarchical, heteronormative possibility space”. But with laughs.

Why so much whipping, I ask Phillipson over herbal tea in an east London bar. “What?” she yells, as a band starts their soundcheck downstairs. Last year, you published a poetry collection called Whip-Hot & Grippy, I yell back. Now you’re installing whipped cream in the most famous public space in Britain.

“Whipped sounds propulsive, plosive, doesn’t it?” she shouts, giggling. “Filled with energy.” There’s something else, too. “I’m really interested in how we give ourselves away in language, how we can’t stop dribbling out stuff in our words and through our bodies.” Freud had the same thought when he invented psychoanalysis, but didn’t explore it in the funny, disarming and programmatically strange way Phillipson does in her art.

That said, she’s aware that The End, as her simulated whipped-cream sculpture is called, puts her art in the public crosshairs as never before. Usually, her audiences are the art world cognoscenti, as steeped as she is in postmodern theory. Now, though, she’s going to have to handle passersby in Trafalgar Square. She got a taste of how the public might react when her maquette for the fourth plinth was displayed at the National Gallery along with other contestants’ designs. One guest book entry went: “They’re all shit.”

What such rude comments fail to appreciate is that The End is an unwitting inversion of Ken Dodd. “What a beautiful day,” said the late comedian, “for filling your trousers with ice-cream, sticking a cherry on your head and saying, ‘How’s that for a knickerbocker glory?’”

Unlike Doddy’s, her knickerbocker glory is apocalyptic: its unstable load, she says, is monument to human hubris and impending collapse. The End will consist of a steel frame covered in layers of foam and wrapped in a glossy surface to look like whipped cream. It will be topped by a cherry with a huge stalk. Fingers crossed, it’s going to defy gravity like the Leaning Tower of Pisa. All that is solid melts into air, wrote Marx; Phillipson hopes her sculpture won’t do that. And that’s odd for the artist: her oeuvre up to now has been mostly perishable – now it is going monumental.

I only know Trafalgar Square from protests. But it is the centre of hubris and data collection and I'm riffing on that

“The context is everything for this piece. I only know Trafalgar Square from protests [she’s sporting an anti-Tory lapel badge] or that time the Pet Shop Boys played there. But it is the centre of hubris and data collection and I’m riffing on that.”

Hence two oversized beasts clinging to her sculpture: one a giant fly sucking up cream, the other a drone sucking up visual data. The former was inspired by David Cronenberg’s 1986 film in which Jeff Goldblum mutates into the eponymous fly. “Disgust can be so engrossing,” she says.

A live feed of Trafalgar Square by a drone camera, accessed through a dedicated website, will give a sculpture’s eye perspective. Phillipson insists that, unlike the CCTV cameras that ring the square, her eye on the square won’t be collecting our data 24/7.

But why is her cream sculpture called The End? The academic Esther Leslie muses in a new monograph about Phillipson that the sculpture may seem to evoke the climate emergency, the end of the welfare state, the death of democracy, the murder of truth, the end of privacy. What Phillipson seems to be lamenting is not one end but many, including the passing of the kind of intimate egalitarian relationship we used to have with animals.

‘Eggs are potential lives’ … My Name Is Lettie Eggsyrub at Gloucester Road underground, London. Photograph: GG Archard

This concern runs through most of her work. For a year from June 2018, London tube travellers passed her installation My Name Is Lettie Eggsyrub on a disused platform at Gloucester Road underground station. Scrawny chicken legs dangled from video screens. Pop-art splodges of eggs in orange and white juxtaposed with films in which eggs were cracked, whisked, cooked and put on sandwiches. “There are all these forms of torture we subject eggs to and I wanted to remind people that these are potential lives,” said Phillipson at the time.

Now the artist, who is vegan, has made an extraordinary audio-collage for Radio 3 called Almost Gone, in which she meditates on the fate of spring lambs to the sounds of baaing. “Listen to a lamb and you’ll find all the traits you need in a friend,” Phillipson says. “Gentle, sisterly, eat food from the ground.” Instead of becoming our friends, these lambs are on the dusty road to death.

Before being humans, or ideas, or genders, we are, primarily, animals. And yet we refuse it, because it would mean relinquishing so much of our power

What she yearns for is what we lost 400 generations ago, when we started to farm and make animals our slaves or food. Morton calls that moment the Severing; Phillipson’s art is, perhaps, the Healing. “Before being humans, or ideas, or genders, we are, primarily, animals,” she writes in the monograph, “and yet we refuse it, because it would mean relinquishing so much of our power. Our treatment of non-human animals is, I think, one of the greatest unacknowledged atrocities – tragedies – of our time.”

Almost Gone is a half-hour journey from a patch of grass to deep space, mixing music sampling, weather forecasts, psychedelic literature and imagining messages from the beyond. “It involves thinking of our ears as dustbins being sold to, hearing other people’s noise, enchantment and disgust.” You should listen to it at high volume in the dark, she says. “If it’s disturbing, it’s because the world is disturbing.”

Although Phillipson was classically trained in piano and violin, she stresses her work as a DJ in the creation of this deranging soundscape. Her first job was in a record shop when she was 16, and soon after she bought decks, becoming a DJ specialising in house, jungle and drum’n’bass in her native London and Pembrokeshire, where she spent much of her teens. She describes that time as an idyll of collective euphoria, performing in barns and fields and being pursued through west Wales by police trying to enforce the Criminal Justice Act.

‘Humans are, primarily, animals’ … 100% Other Fibres, 2016. Photograph: courtesy of the Artist

Phillipson once said: “I’m a poet, because I want to spend five hours writing three words.” She has been lucky enough to realise that dream, and several others besides to become a triple threat: visual artist, poet and musician. In June, she will take over the Duveen Galleries in Tate Britain with a vast video installation. She’s so much in demand that she has become ridiculously productive – writing three words in five hours is no longer enough. I once asked the director Steven Soderbergh why he worked so hard. “Cause I’m going to die,” he replied.

“I’m the same,” says Phillipson when I tell her this. “Sleep when you’re dead. I’m fortunate to be in demand.”

She knows good fortune would be nothing without free education. “This worries me – how hard it is for younger artists to survive now, or even to feel entitled or be able to go to art school, without independent financial means.”

She went to a local comprehensive in London, before studying at Cardiff Metropolitan University, Central Saint Martins and Middlesex University. She recalls that when she applied to do a fully funded drawing course in the early 00s, course fees were waived because she was signing on. Now in her early 40s, she belongs to the last generation that had university grants and negligible debts. “Crikey, it’s had an impact – permitted me to do so much.”

One of the ends she may be on about in her whipped cream sculpture, then, may well be the imminent death of art as anything but luxury goods made by and for those with money. If so, Phillipson could be one of art’s last weirdos. Which is good enough reason to celebrate her.

• The End is unveiled on 26 March. Almost Gone is on BBC Radio 3 on 15 March

• This piece was corrected on 12 March: Phillipson’s 2014 installation was shown in New York, not Brussels, and her drawing course, not her PhD, was fully funded