After a long day on the campaign trail across the south of England, Rachel Reeves was heading back to her home in London to do some late-night cooking with leftovers from Sunday lunch.

“I don’t like waste,” she said, when asked if she was as cautious in her own household as she has promised to be with the nation’s finances, despite pressure from within the Labour party to be more ambitious.

“We had roast lamb at the weekend. I’m worried there’s a lot of lamb left in the fridge, so I’m going to make a curry when I get home late this evening and whack it in the freezer so it will be ready after the general election.”

Reeves relishes her reputation for fiscal prudence and has promised to be the “iron chancellor” who will get the UK economy back on track. If the polls are accurate, her lamb curry will end up in the freezer at 11 Downing Street.

It would be a historic moment. In the hundreds of years that the post has existed, it has only ever been held by a man. In the last 14 years alone, there have been seven Conservative chancellors.

“I hope that one of the things that I can do if I become the first ever female chancellor of the exchequer is show that there are no jobs that women can’t do. This will be the last big job in government that a woman has never done.

“You’ve had a woman defence secretary, foreign secretary, home secretary, prime minister and speaker of the House of Commons. We’ve never had a woman in charge of the nation’s finances. I think that carries with it a big responsibility … It’s the last glass ceiling in politics.”

Sitting at a high table in the staff canteen at a Morrisons supermarket in Swindon, Reeves said the prospect of becoming chancellor made her reflect on the Labour women she admired across history.

They include Ellen Wilkinson, who as education minister in the 1940s raised the school leaving age; Barbara Castle, who as employment secretary in the 1970s brought in the equal pay act; and Harriet Harman, who introduced the equality act as minister for women in 2010.

“I feel like in many ways, I’m standing on their shoulders, and the way that they have made achievements for women – I want to do the same,” she said. Her own focus will be on eradicating the gender pay gap.

But during each of the periods they were in office, their governments invested huge sums of money in public services. In contrast, Reeves has warned about the tough choices ahead; the Institute for Fiscal Studies has spoken of a “conspiracy of silence” over looming spending cuts.

Despite pressure to invest more to avoid more crippling austerity, she refuses to speculate on what she would prioritise if she could loosen the public purse springs. “I’m not going to do that. I don’t want to make promises without saying where the money is going to come from. There have been so many broken promises by politicians these last few years,” she said.

“I don’t want to be one of those politicians that says things without knowing how I’m going to deliver it. Of course there’s more that I’d like to do.”

Reeves denied that she was looking for a “doctor’s mandate” in a first Labour budget this autumn, arguing that the state of the public finances is so bad that they will need major surgery to correct.

“We know that things are bad. I know the inheritance is going to be really tough. It’s why, when you say, ‘Do you want to do this, and that?’, I have to say that we can’t do everything that we might want to straight away.

“I wish the inheritance was different, I really do …. Do I wish there was more money? Do I wish that public services were in a better state? Of course I do. But you don’t get to choose your inheritance. But we will start to turn things round.”

Labour has ruled out putting up income tax, VAT or national insurance. Reeves denied that Labour was looking at other tax-increasing measures that would raise smaller sums.

“No, what we’re seeking is a mandate to grow the economy. Instead of tinkering around with taxes, which is what the Tories have been doing these last few years, we are going to go all for growth.”

Her repeated insistence that tax and spending are not the only levers Labour can pull, suggesting they could instead secure the highest sustained growth in the G7, has attracted scepticism.

“We’re going to crack on. We’ve been in opposition for long enough. There’s lots of things that we are ready to go with,” she said.

In the first six months in office, Labour would update the national planning framework and significant infrastructure list, making it easier to get planning permission for onshore windfarms, pylons and pipelines. It would also bring back housebuilding targets for local authorities.

Reeves, who has always been more willing than some in the party to talk about the downsides of Brexit, said that Boris Johnson’s deal had “sold Britain down the river”, leaving many businesses, especially small ones, struggling.

“There are concrete things that we can do to improve those relationships,” she said, citing a veterinary deal to make it easier for farmers and fishers to export, tackling bureaucracy for travelling artists and musicians, and mutual recognition of professional qualifications.

Reeves said she would roll out the red carpet for foreign investors – as the French president, Emmanuel Macron, had offered to do for British financiers after Brexit – with a big investment summit in the first 100 days.

“Yes. We need that investment. If we’re going to invest in our infrastructure on the scale that we need … then we need global investors. It used to be that Britain was a byword for stability … That’s disappeared these last few years, and we want to bring that back.”

She dismissed suggestions that the UK would struggle to hit growth of 1.5% in the next five years. “Why not? Under the last Labour government, average growth was 2% a year. I’m confident we can get our growth back up. I’m not going to put a number on it.”

Yet despite Reeves’s discipline and focus on Labour winning power, she said she had no ambitions to become Labour’s first female prime minister. Clearing up the used teacups in the canteen, she replied: “No, not really. I just want to be chancellor. You know that.”