IT'S not the blood that would be the problem, reckons Neve McIntosh.

Arterial spray, the deep shocking red of bodily fluid: that, she could cope with. "I'm not that squeamish. I've surprised myself sometimes, doing bits of first aid, with what I can put up with," she says.

No, it's the sense of responsibility that she couldn't handle. The knowledge that just one mistake could have permanent consequences. "I would be petrified about that."

That's why, she says, she could never be a nurse in real life. Instead, she'll settle for just playing one. In writer Jed Mercurio's new Sky 1 drama Critical, that's just what she does. Playing nurse consultant Nicola Hicklin, "basically the deputy boss of the entire emergency and trauma unit".

Critical is a high-tech, high-end and high-energy drama (are there really hospitals as high-tech as that, you do wonder, watching it). And there is a lot of blood. Special effects lovers - look out for the exposed beating heart in episode one. "It's one patient, one hour, one life to save," is its star Lennie James's pithy summary. According to McIntosh: "It's a wee bit like ... do you remember Your Life In Their Hands? But with actors."

The Scottish actor has previous on the medical ward. On her CV - as well as appearances alongside David Tennant in the drama Single Father and Tennant's Doctor Who replacement Matt Smith in, umm, Doctor Who - there's a role in Mercurio's breakthrough drama Bodies 10 years ago. Sometimes it seems that the only dramas we do here in the UK are medical and police based. McIntosh agrees. "Though even when I did Bodies with Jed we wondered - 'God, is there room for another medical drama?'"

It probably depends on whether it's any good or not. After all, Mercurio's last project prior to Critical was Line Of Duty and that was pretty decent.

And the truth is, we like police procedurals. We love medical settings. "It's a natural drama, isn't it?" suggests McIntosh of the latter. "Can we save this person? No matter how badly damaged their body is, can we actually do it? You've instantly got that there."

But we haven't made any proper introductions yet, have we?

Neve McIntosh - a stage name; she's still Carol to her friends and family - grew up in Paisley. She possibly first came to your notice in the Bobby Carlyle movie Plunkett & Macleane, or probably opposite Douglas Henshall in the BBC drama Psychos (she played a nurse in that too, come to think of it). Or maybe you caught her in Weegie lipstick lesbian drama Lip Service. And you'll definitely have seen her playing Madame Vastra, a crime-solving lesbian lizard (or a "lizbian" as some wags quickly labelled the character) married to a human in Doctor Who.

She's at home in London when we speak but by the time you read this she will be in New York, performing in David Greig's play The Events, off Broadway. A dream fulfilled.

What does she look for in a role? "The scope to do something interesting I've never done before with a character. And a decent story arc as well. So you don't just feel you're a device, a foil for the main character. Or just the woman giving information on the phone in the background."

She's always been outspoken about her desire to avoid the eye candy role: the subject of the male gaze and nothing more. You wonder, though, how easy that is to do. "It's hard because it's completely out of my control. You go for an audition and you meet a director and you find that they don't want you. You have to have a pull with them; that they understand what you want to bring to it. That you don't want to be the pretty little thing.

"It's hard to get the downtrodden working-class wifey sometimes because, 'you don't look like it'. Well, that's weird because I grew up on a scheme in Paisley. But everyone's got a viewpoint about what you should look like and it's tainted by prejudices and assumptions."

We are speaking just a week after Julie Walters told a newspaper that "people like me wouldn't get a chance today" (by which she means people with non-RP accents who grew up on council estates. In short, people like McIntosh too).

"I've definitely seen a bit of a change," suggests McIntosh. "If you look at Sunday night there's a lot of Downtons and Upstairs Downstairs, isn't there?" Then again, she says, she's played ladies and wifeys. "It's a slightly different thing being Scottish," she thinks.

At least there are writers like Jimmy McGovern, she points out, "so it is still there. I think maybe it isn't seen as important as it was back in the 1970s and 1980s.

"Then you've got something like [Channel 4 series] The Mill. It just felt a bit thinly done. The way some upmarket, posher things are as well. You just think, 'Really, is that it? Pretty frocks and an RP accent?'"

The real problem, she says, is working-class kids being able to afford to go to drama school in the first place.

"I do worry because it takes all types to make our culture, to make our art. We need it to be available to all. In Scotland there are still grants, and I suppose there are scholarships that some of us with the money that we've made have set up, but really there should be something from the state as well."

All of which said, this is a good time for British TV drama. Critical is another example of that. We have taken on board the HBO model and there's a greater ambition now, even in medical and police dramas. McIntosh agrees. "For a little while there I was thinking, 'I don't want to be in anything on British TV'. I didn't watch any of it because it was rubbish. It has got a lot better."

And then there's Doctor Who. Which, curiously enough, might be the most controversial thing she's ever been in. Not because of the lizard bit (three-and-a-half hours in make-up every day). It's the lesbianism some people have problems with. The scene where she "kisses" her wife Jenny during the first Peter Capaldi episode (strictly speaking in plot terms she was sharing her breath) was cut when the programme was broadcast in Asia, where the promotion of homosexuality and lesbianism are banned by the broadcast code. Neve, you're trying to turn everyone gay, aren't you?

"Oh really? Because that would be a horrific thing," she laughs. "I loved that, because there was no big drama made about it. We just turned up and it was like, 'I'm married now', and carried on with the story. I think if it's a big deal people need to look at themselves."

She hopes she'll play the part again at some point. "I've only done one with Peter. I want to do more.

"It's very tiring but it's the most fun you could possibly have. They give me a sword. They give me a wife. I'm in lovely frocks and I get to run around being kick-ass. What's not to like?"

Who's her favourite Doctor, then? "Don't ask me that. That's a terrible question. Growing up, my favourite, favourite Doctor was Tom Baker ... I'll have to go with Matt. He was my first doctor. The first one I worked with."

Why did McIntosh want to be an actor in the first place?

"Probably because I wanted to be the centre of attention. But I'd like to say something a bit more intelligent than that."

She has a think and starts to talk about when she realised how much is involved. "When I realised how much work it takes to try to be someone else psychologically. Not physically. Anyone can put weight on. It's how you change your attitude to things, how you improvise, having your character whole. So you know how your character would react if some guy ran through b****** naked. Some might chase him. Some might go, 'Yeah, whatever'."

How would Neve McIntosh react? "I would just laugh and laugh. Especially in this weather."

Critical starts on Sky 1 on February 24