Jodie Whittaker has her "Beth hair" on today. She's gone brown because she's filming the third series of ITV's hugely successful drama Broadchurch in which she plays grieving mother Beth Latimer. It's not her favourite look, she admits.

"I'm not a massive fan of having brown hair because I don't wear make-up and I always look a bit drawn and a bit tired," she tells me. "I get recognised a lot more when I've got brown hair, whereas usually in my life I'm blonde. I would be straight in with a bottle of peroxide."

"When season one came out I did alright because I was peroxide blonde. I get much more recognised when I've got "Beth hair'."

It might be that or it might be the fact that she has a growing reputation as one of Britain's finest actresses. There is more evidence on display in her latest film Adult Life Skills which is out now. It's a bittersweet comedy drama about a woman who has lost her twin brother and is struggling to adjust to adulthood. She's living in her mum's garden shed, wearing bras that are still wet from the wash and getting cut short in public.

Is that something that has happened to you in real life, Jodie? When was the last time you went to the toilet in the open air?

"Oh this is really bad," she says. "I know this exactly. On the set of my next film Journeyman we were filming in a wood on a country path. I and the costume and the continuity lady had to rig up some big tarpaulin thing. They just held it over me. There were loads of dog walkers, so I was mortified. But I was very well hidden and I'm not followed by paparazzi so there was no chance of me being on the front of The Sun."

Whittaker, 34, is in Edinburgh for the Film Festival today. She is a sparky livewire of an interviewee, all exclamation marks and enthusiasm. The accent is still pure Yorkshire though she's lived in London for years with her husband Christian Contreras and, since last year, her first child.

Her new movie Adult Life Skills is Yorkshire-based. It's also sweet and sad by turns. What with Broadchurch and this she's becoming something of a go-to girl for grieving, I suggest. Actually, she thinks, the common theme is more loss than grief. "I think most cinema explores loss in some way. In ET there's the loss of the father. In The Goonies the loss of childhood.

"Grief is a specific thing because it's about death. But loss is all-encompassing. I think if I go through my CV most of my characters would have lost something. It's a theme that comes up a lot."

Born in 1982, Whittaker grew up in the west Yorkshire village of Skelmanthorpe where, yes, she saw ET and The Goonies (her favourite film). She wanted to be an actress from a young age. "It was never a decision for me. I was just really lucky. I wanted to be an actor from being a little kid."

It was partly because she wasn't academic enough to be anything else, she says, partly because she seemed quite good at it. "But I also have a massive ego," she admits happily.

"I just was really naïve. I started saying when I was 15, 'I'm going backpacking for a year when I'm 18. I'm then going to audition for drama school in London.' And I do not know now as an adult of 34, looking back on the troubles and obstacles of life, how that happened. But it did."

It's possibly because she's simply very good at it. She made a name for herself in her debut film Venus, playing opposite Peter O'Toole and has since appeared in numerous TV series and films including One Day and Attack the Block.

But Broadchurch is the one that gets her recognised. Did she realise while filming the first series that it was going to have quite the impact it had?

"I think none of us really cared actually. I know that sounds awful but when you have such a good time on something what happens afterwards is for the producers and for ITV to worry about.

"But when we were shooting I can remember having a conversation with a friend saying 'if I'm terrible in this I've really let myself down because I've been given opportunities to work in a really fantastic way. Because all the other actors were amazing, the crew were amazing and the writing is fantastic. That's essential. That's what it comes down to me. The writing."

It was the fact that when the first series of Broadchurch aired people quickly saw it as appointment telly that was thrilling, she adds. "People were watching it every week. I haven't remembered that for a long time for a TV show so it felt really exciting to be part of that."

Even if it does mean you get recognised when you have your "Beth hair" on.

Adult Life Skills is available Video on Demand.