Despite the fact she has a new book out and a skin-care line on the shelves on April 1, Foster Blake is focused on a big life-changer of an event due to occur in late May.

"We feel very fortunate to have fallen pregnant," she says. "We're actually beside ourselves.

"Hamish particularly is very excited; he's wanted to be a dad since before he was born, and I'm extremely excited and looking forward to a whole new focus."

The pair were firm friends when they collaborated on a book in 2009, aptly called Textbook Romance. "How to find the guy, make him fall wildly in love with you and keep it that way," it was tagged. Foster Blake must have followed her own advice. They soon began dating and were married in secret on December 11, 2012, Blake's 31st birthday. And now they're having a baby.

For a relationship that's been somewhat played out on the social pages, on radio during Blake's popular Hamish and Andy program with Andy Lee, even through their matching columns in the News Limited Sunday magazine, listening to Foster Blake talk about her husband and how they're coping with the idea of a baby still seems like I'm intruding a little.

"I've had incredible support from my husband and his family and my family and friends who have been down this path," she says.

"We've received some amazing advice from left, right and centre, and whatever confusion there was has been stripped out of me."

At this point I want to tell her not to listen to any of it, but she's a sensible girl and continues.

"But I realise you can read all the literature and think you're prepared, but you can't really be prepared until the baby arrives. We'll just have to wait and see how we go when it arrives."

They've deliberately not found out the sex of the baby - "we like surprises" - and have their Melbourne nest in order and are looking forward to a little down-time to prepare for the birth.

"It's a whole new kettle of fish for us, trying to get everything done before then," she says.

"It's a real deadline, and it's our first time, so we've got to clear some space so we can get our heads around it."

So let's get the publicity for the book out of the way. The Wrong Girl is Foster Blake's fourth novel. (As well as the how-to Textbook Romance, she's also written Amazing Face, a how-to guide on beauty and make-up.) The Wrong Girl is another story firmly set in the chick-lit genre. Thirty-something girl with relationship and career doubts, a bit of sex, a lot of humour … nothing that will make you think too hard - just a good rollicking read for those in a similar situation.

"It's by no means a serious novel. I've never been a serious writer, so why start now," she says with a laugh. But she does have a knack for character and situation and selling books.

While her previous novel, The Younger Man, touched on the whole idea of marriage and babies, she made a deliberate choice with The Wrong Girl to set the story firmly in singledom. To get it out of her hair, perhaps?

"I actively and consciously pulled back from marriage and babies with this one.

"While I want my readers to grow with me, I didn't feel as though I had completely finished in that single-girl arena yet; I still very much enjoy playing there.

"I'm sure once I've had a baby, whether I want it to or not, the next stage of my life will infiltrate my work.

"But for now I've still got plenty of single girlfriends; doing the Agony Aunt column for Cosmo, I'm still hearing plenty of angst and questions from women in their 20s and 30s, questions about relationships and careers and life choices."

She describes The Wrong Girl as something of a coming-of-age story.

"While there's still a romantic narrative, there's a big focus on Lily's career, and it's about her growth and development in that area, too."

Foster Blake grew up in the Southern Highlands, studied media and communications at the University of NSW, and worked in magazines, including a three-year stint at Cosmopolitan as its beauty and lifestyle director.

She was quick to embrace the online world. She developed beauty blogs fruitybeauty.com.au and primped.com.au, and was a contributing editor at Mamamia.com.au. She has more than 36,000 followers on Twitter (Foster Blake and Blake announced both their engagement and wedding via Twitter - what are the odds we'll first hear of the baby this way?) and a website at zoefoster.com.au.

Her first novel, Air Kisses, was published in 2008, Playing the Field in 2010 and The Younger Man in 2012. In between came the how-to books and an app for Amazing Face.

"I'm at my most productive when I'm busy," she says.

"If there's a void I fill it with nothing and waste too much time on the internet and watching bad television.

"When I'm super-busy I'm at my most powerful."

Foster Blake says her secret is not taking herself too seriously, admitting that women of a certain age, those trying to build careers and relationships, can fall into that trap too easily.

"Not taking myself seriously has always been my mantra. Everything is allowed to be fun.

"Humour is very much the framework by which I live my life, in terms of how I write, my blog, with my husband.

"So much of our life is spent laughing and having fun. We think it's a pretty lucky way to live life. We feel very blessed in that sense and I feel sad for people that don't get to engage in that aspect of life as much as we do."

She says having the baby will be like having another kid in the house.

"That's the most exciting part for us - that we'll have this funny little person making us laugh."

■ The Wrong Girl, by Zoe Foster Blake. (Michael Joseph, $29.99.)