The SNP should be less confrontational and co-operate with political rivals – and the English, Scotland’s First Minister has said. Nicola Sturgeon wants to build a “progressive alliance” capable of propelling Ed Miliband into 10 Downing Street after May’s UK general election, she told i in an exclusive interview.

The SNP will very likely refuse to join a coalition with Labour, Ms Sturgeon said, if neither the Conservatives nor Labour wins a majority – the most probable result according to current polling. She would prefer to support a Labour minority government “on a case-by-case basis”, an arrangement known as “confidence and supply”, so long as Mr Miliband agreed to moderately increase public spending.

The SNP wouldn’t enter into a coalition unless Labour was willing to scrap Trident renewal, she said – a position Labour will not countenance. What’s more, the fate of the current junior Coalition partners, the Lib Dems, alarms Ms Sturgeon. “I think it would be very unlikely to have the SNP in a formal coalition in Westminster. I’m not ruling it out entirely. I think it’s more likely if we were to be in this scenario, that the SNP would act in an issue-by-issue, confidence-and-supply arrangement.”

She could yet end up in the curious position of supporting a form of government she wants to see abolished. But Ms Sturgeon has a plan, of course. If the SNP wins a large block of seats and can put Mr Miliband in Downing Street, she intends to prise from him new powers for Scotland – and to push the case for Scottish independence again. “We will always seek to use the levers we have,” she said. “I’m not making any secret of the fact I still believe in independence. We’ll continue to argue the case."

Sturgeon on...

Women in politics and the boardroom

Quotas are necessary. They’re a blunt tool. But if we had a real meritocracy now we’d have a gender balance. Progress is painfully slow.

Coalition welfare cuts

Women have been particularly hard hit along with the disabled, and the poorest 10 per cent. The cuts are a false economy. They [the Coalition] are not cutting spending, they’re just transferring responsibility for spending. We’re having to invest tens of millions of pounds to mitigate some of the effects… so it’s not an actual cut.

Comparisons with Alex Salmond

One of the things I’m just not going to do as SNP leader is obsessively look for differences with Alex Salmond – and almost in a way saying, “Oh I’d do this better than him.” Alex has been one of my closest colleagues for 20 years. He remains a huge part of the SNP team.

Deficit reduction

The whole approach the UK Government is taking is wrong. It’s cut at all costs. Slash and burn without thinking of the consequences. We need to be focusing on investing in infrastructure, innovation, and the challenges of productivity if we want the economy to grow sustainably and solidly. If we want to have public services that are able to deal with the ageing population we need to invest properly, and I don’t want to see an approach that penalises the poorest people in society.

Whether she or Alex Salmond will call the shots

Our MPs on a day-to-day basis will take decisions on how they’re voting. But I’m the leader of the party and in terms of our overall strategy and how we vote on key issues, then ultimately those decisions will be mine.

Greece’s Syriza party

I wouldn’t model ourselves on them. But it’s part of a bigger movement.

Opposing the liberalisation of drugs laws

I think the evidence leads us to that view.

Using “Westminster” as a term of abuse

Do I mention Westminster negatively? Guilty as charged. Westminster as an institution needs to be seriously shaken up, given the fright of its life.