She has an Academy Award for playing Virginia Woolf in The Hours, a star on the Hollywood Walk of Fame, and she graced a 2009 Australian postage stamp. You'd imagine that Nicole Kidman would sigh wearily at the prospect of winning Yet Another Bafta. Instead, she greets the news of a nod for her supporting turn in Lion as if she's won the lottery. There can't be much space left in her good glass cabinet, surely?

“Ooh, no, I definitely have a space,” she says, excitedly. “And I can’t wait to tell my daughters.”

Deep into awards season, Kidman has already raised eyebrows with a jolly appearance at the Golden Globes ceremony, a shindig that is seldom mistaken for a temperance rally. At least one reliably hysterical tabloid was horrified by reports that the 49-year-old – a Guess Your Age app would say 33, tops – had crashed a boring red carpet interview with Tom Hiddleston and had – oh, the humanity – brushed pizza crumbs off her dress. We should expect no less from the woman who greeted the furore over The Paperboy – a film in which she memorably relieves herself on Zac Efron – with a shrug of her freckled shoulders.

“Oh dear,” she says, with her tongue firmly in cheek. “When I’m at press conferences and whatever, my dry Australian humour doesn’t always translate. But that’s how we do most things: with humour. And at my age, I’m coming into that place where I think: Ah, who cares? I can be who I want to be. I do have an earnest side. But it’s calming down.”

Otherworldly creatures

I'm not sure what I was expecting from Nicole Kidman. For much of her life – and mine – she was one of the most photographed women in the world. As long ago as Dead Calm, made when she was only 21, she looked like a natural-born movie star. Perhaps as a by-product of her vast celebrity, she has often seemed as ethereal as the otherworldly creatures she portrayed in The Others, Birth and Rabbit Hole.

But in real life she's . . . well, real. Years and distance have not wearied her Australian accent and irreverence. And she certainly has the gift of the gab. It is often noted that Kidman – who was married to Tom Cruise from 1990 to 2001 – doesn't discuss Scientology. She certainly covers all other bases. Half an hour into our conversation and I could write a book. We've covered everything from the rising traffic levels in Nashville to shooting Far and Away in Kerry. I know her Irish family left the Dingle peninsula for Australia in 1839. I know her sister, Antonia Kidman, a journalist and TV presenter, has just finished a law degree. I know that Jane Campion's nickname for Kidman is "Unicorn".

“I’ve always done things a bit differently,” she laughs. “My mum always says I was left in the garden. That I’m a changeling. And I say: ‘Mum, that’s terrible!’ But she insists it’s a compliment. That it just means I’m a bit different from the rest of the family.”

A changeling unicorn?

“Oh yes. I’ll take that.”

The rarity of that species may account for Kidman’s disarming demeanour. She far more fun than you might have guessed and about 10 times more emotionally available: “I do do things differently,” she nods. “I cry very easily. I understand other people’s emotional states very easily. I see that same empathy in my oldest daughter. She’ll sit there watching a movie and she’ll be heartbroken. And she’ll take a long time to recover. I was that kid, too.”

Feminist and proud

Nicole Mary Kidman was born in Honolulu, to Antony Kidman – a celebrated biochemist, clinical psychologist and author – and Janelle Ann, a nursing instructor, scientific editor and member of the Women’s Electoral Lobby. She was raised feminist and proud in Sydney, an upbringing that would allow for greater versatility as a performer.

“I’m just not attached to my physical identity,” she says. “When I have to play a character, I really relish physical change. As an actor, that’s what you’re supposed to do. That’s what we were taught at drama school. Change the way you walk. Change the way you talk. Change your physical being. Change your nose. Trouble is, when a woman does it, it’s a big deal. Oh, she’s got different hair! I don’t care about that. If you’re trying to play someone like Virginia Woolf, you sit down with others and say: show me how I can become this person.”

She’s more than her appearance but she is, nonetheless, happy that she “looks Irish”. If she has one regret, she says, it’s getting out the straightening iron too early and too often on her red curls.

“I just played someone with natural curly hair and no make-up,” she says. “What a relief! My littlest daughter has the exact same hair I did. I look at that hair now and think: ‘Ooh, you’re not to do anything to that beautiful hair.’ Now my curls are just frizz really. I wish I had valued them before they got that way. I can sneak up on my daughter to touch hers. But she tells me to leave them alone.”

Kidman’s last years in the Hollywood whirlwind – post-Cruise, there was some highly publicised stepping-out with Robbie Williams and Lenny Kravitz – were defined by “a lot of exposure” as she delicately puts it. It could have been worse: she did skip town before TMZ, social media and Rottweiler paparazzi took hold. “I was lucky because I navigated a lot of loss and pain, but I didn’t have to do it as publicly as many actors have to nowadays,” she says. “It’s definitely a different territory now. I’m not sure I would have managed that.”

She laughs: “Luckily, I’m not as interesting as I used to be.”

Gypsies

These days, Kidman savours a “quieter, nourishing pace of life” in Nashville, Tennessee, with the New Zealand-born country singer Keith Urban, her husband of 10 years, and their two daughters, Sunday (7) and Faith (5). The family are close – if Nicole is on set, the rest of the clan come with. Ditto when Keith goes on tour. “We’re gypsies,” she says. “We can get up and go anywhere at any time. The concept of home for us, is us. As long as the family is together then we’re home.”

When she won an Evening Standard award for her turn as X-ray crystallographer Rosalind Franklin in the West End production of Photograph 51 last year, she was keen to share the credit. "I brought it home and said: 'We've won this. We earned this together because you moved to England so that I could do this. This belongs to our family.'"

Movie lore tells us that the sets of Stanley Kubrick's Eyes Wide Shut and Lars von Trier's Dogville were not the jolliest of working environments. Kidman, a tireless cheerleader for auteur-driven cinema, is having none of it.

“I’m drawn to visionaries,” she says. “For me, an auteur is someone educated enough to micro-manage cinematography, editing, lighting – every single step of the process. Other people are there to augment and facilitate their vision. And it’s a massive advantage to work with someone who has a vision. Because you have a leader. You are part of a larger thing. I’ve always said that Kubrick was a philosopher. As is Jane Campion. As is Sofia Coppola, who I’ve just finished working with. I’m drawn to those people.”

Idiosyncratic

Kidman cheerfully describes her recent work – think Werner Herzog's Queen of the Desert or the incoming Yorgos Lanthimos curveball The Killing of a Sacred Deer – as idiosyncratic. "I've never been one for the mythology of the hero," she says. "I'm wired to like flaws and tragedy. For as long as I can remember, I have always been slightly offbeat."

The feelgood drama Lion is an exception to the rule. Based on an irresistible true story of an Indian-born, Australian-adopted boy who uses Google maps to find his birth parents, this gorgeously emosh tear-jerker stars Kidman as the adoptive mother of the cross-continent trekking hero (Dev Patel). It was an important project for Kidman, who has come at motherhood every which way: she adopted two children with Tom Cruise, and has two biological children with Keith Urban, one through traditional means and one via surrogacy.

“This is the purest form of maternal love I’ve done on screen,” she says. “Unconditional. Very warm. Once the bond is formed with a child and you are the mother, everything is different. I don’t know that you can fake that. Maybe a great actress could. But I needed to draw on what I knew.”

How did her own experiences with adoption shape her performance?

“They were everything. The primary thing being that desire for the birth mother to know that everything is okay. You’ve had this child, you’ve lost this child, and I want you to know that your child is safe. That’s a strange and powerful union between women. Sometimes, it takes a village to raise a child. And that’s a very beautiful thing.”

Lion is on general release