“I’m very excited, not scared,” says French actress Léa Seydoux when we meet in a London hotel and the size of her baby bump makes it impossible for it not to be a topic of conversation. “I feel that it’s part of nature. I’m not anxious. It’s fun. It’s very magical and seems so strange to me, being pregnant. I love kids so I’m very happy to have one.”

The father is long-term boyfriend Andre Meyer, and Seydoux had a baby boy in January.

Such is her excitement about starring in an adaptation of Jean-Luc Lagarce’s play It’s Only the End of the World that, in the weeks before she took maternity leave, Seydoux wanted to talk about appearing alongside Marion Cotillard and Vincent Cassel in the Xavier Dolon film.

A scene from ‘It's Only the End of the World’: Seydoux (centre) as Suzanne holding court at a family dinner sitting next to Nathalie Bayer (right), Gas​pard Ulliel (left) and Vincent Cassel and Marion Cotillard

Dolan is the mercurial Quebecois director who, with his claustrophobic film Mommy, became the youngest ever person to direct a film playing in competition at the Cannes Film Festival. Not only that, he went on to share the Best Director Prize with Jean Luc Godard. Dolon is a director that actors want to put down everything to work with and it was no different for the 31-year-old actress: “I liked the script and I really wanted to work with Xavier Dolon.”

A stylishly filmed lavish work, It’s Only the End of the World won the Grand Jury Prize at Cannes last year. The play it’s based upon is much celebrated in France, where playwright Lagarce has become one of the most widely produced writers since his death from an Aids-related illness at the age of 38 in 1995.

The film is about a writer, Louis (played by Gaspard Ulliel) returning home after a 12-year absence with the intention of telling his family that he is dying, but his best intentions are undone by the very same crazy family dynamics that made him run away in the first place.

Seydoux plays Louis’ younger sister Suzanne, who dreams of escape and emulating her brother’s successful career, but is also imbued with so much resentment and personal angst that she is often obnoxious. It’s not exactly the kind of glamour role that we are used to seeing the former Bond girl and Mission Impossible star play. “I was a little afraid about taking on the part,” says Seydoux, “because she is very afraid, angry and hysterical.”

Lea Seydoux as Bond girl Madeleine Swann in 'Spectre' (Sony Pictures)

This fear led her to tell Dolon, “I don’t know if I will be able to do it, all I can say is that I can do it.”

The end result shows that, in fact, Seydoux has no problem with playing ugly. I wonder if she did anything out of the ordinary to tap into Suzanne’s mindset, or whether she thought of moments in her own life. The actress shoots down this type of acting approach: “No. I don’t think you have to think too much about it. It’s something that is instinctive. It’s a body language. Some actors maybe need to be angry but I know I can be angry and that it’s within me. So I just think, now I have to be angry and just go for it.”

Director Dolon has described the film as being about the incapacity of humans to love. Seydoux refines this comment by suggesting that “we struggle with expressing our feelings more than we do to feel love. I think that we all feel love, but sometimes we forget and the angriness takes over.”

We saw the angriness take over Seydoux after Blue is the Warmest Colour won the Palme d’Or at the Cannes Film Festival and the Steven Spielberg-led jury took the unique step of awarding the Palme d’Or to both the director, Abdellatif Kechiche, and both its stars, Seydoux and Adele Exarchopoulos. The film is infamous for a seven-minute lesbian sequence featuring the two actresses. However, the director came in for public criticism from Seydoux when she described the shoot as “horrible”.

Seydoux (right) with Tom Cruise and Paula Patton at the ‘Mission Impossible: Ghost Protocol’ UK premiere

I ask if the experience on the film has made her change the way that she chooses roles: “No. It’s always instinctive. You never know what will happen,” she replies. It’s why she wasn’t fearful of Dolan, who has a reputation as an enfant terrible. “I felt that working with Xavier was something that I wanted. I don’t mind the reputation. I love his films and I like to be driven by the energy and the talent. I like to work with talent… I like to be directed and sometimes I feel that a director can be lazy.”

She elaborates: “I like to be a little squeezed, or shaken, but I like it when it’s subtle. Not, ‘Hey you’re a bitch, now cry’. Directing is very interesting.”

Seydoux comes from one of France’s most famous movie families. Her grandfather Jerome Seydoux is the chairman of French studio Pathe. Other family members are film producers and her great uncle Nicolas Seydoux is president of Gaumont. Yet having entered the family business as an actor, she’s in two minds about directing. “I would love to direct, but I don’t know if I can make a good film. So directing actors, yes, I would love to do that, but to be a director, in the sense of making a film and the technical aspects, I don’t know.”

Her early success as an actor saw her quickly move to Hollywood. She says of acting alongside Tom Cruise in Mission: Impossible – Ghost Protocol, “With Tom Cruise you always see the star. His face is so famous. But there is a moment where you have the person and interact with him and you forget his status. Some people you forget that they are stars. I felt that more with Daniel Craig than Tom Cruise. Also that may be because Daniel’s more accessible.”

She says of the Bond experience: “When he [Craig] did the first James Bond, I was young and so for me, he is part of my conscious as being Bond. He is part of my imagination. I spent a lot of time with him shooting the film and at a certain moment he became Daniel, not a star. With Tom Cruise it’s different. He’s not that accessible, but he’s nice, he’s really nice with me.”

Before making It’s Only the End of the World Seydoux took a year off work but she has a busy schedule ahead, having signed on to work opposite Ewan McGregor on Drake Doremus’ Zoe, a sci-fi drama about researchers designing the perfect romantic relationships, and also Thomas Vinterberg’s submarine disaster movie Kursk.

When we spoke she admitted to having some trepidation at returning to work a couple of months after having her child. “I will need help,” she admits. “I don’t know how I will be able to work on the project. Because you need to be focused when on set and open to the film. I don’t know when you have a baby – when he cries at night and stuff – how do you manage when you arrive on set in the morning?”

Seydoux is about to find out the hard way, which is how she seems to enjoy it.