The Conservatives like to sell the public a promise: do “the right thing” – work hard, look after your family, pay your taxes – and in tough times, the welfare state will be there for you. But here’s a snapshot of what could happen to any one of us if bad luck hit. Denise, has been a nurse for the best part of 30 years, but since she became too ill to work, she’s been left to live without sickness benefits for five months and counting.

Denise, now 48, trained as a mental health nurse straight out of school and tells me she has worked all her life. It wasn’t easy. In her mid twenties she was diagnosed with bipolar disorder, and by her thirties, as she raised a young son in Leicester, she developed fibromyalgia. With it came pain and exhaustion: each joint hurt to move, and for months she needed a wheelchair and hospital car to see a specialist. “At times, I actually crawled on my hands and knees to attempt to make us a meal,” she says.

Over the next 15 years, Denise did what many with long-term illnesses will be all too familiar with: she pushed herself to keep working – going part-time to try to manage her bipolar, pain and fatigue. When things were at their worst (in 2011, she had major surgery on her spine), she lived off the out-of-work sickness benefit, employment and support allowance.

Last winter, again, Denise tried to work. After being on ESA for almost three years, she felt well enough to move to Bristol to be near her partner and take a job nursing in a women’s secure hospital. But after eight weeks, the impact of the work on her mental health was too much (“helping pregnant women with psychiatric problems … it was very emotional,” she says) and she had to give it up. She got by on company sick pay – half her wage – for three months, but by April she was earning nothing at all.

Ask most politicians and this is exactly when they’d say the safety net would kick in. But when Denise contacted the Department for Work and Pensions to say she’d had to leave her job, she was told she was no longer eligible for out-of-sickness benefits – despite receiving them only four months earlier. Because she’d been off the benefit for more than 12 weeks, in the mire of DWP rules, technically Denise was making a “new claim”, judged on a different tax year – meaning the DWP could now rule her as not having enough national insurance points to get the benefit.

Worse, Denise was told she wasn’t eligible for the alternative either – the type of ESA based on income, rather than NI contributions. Why? Because she was now living with her boyfriend.

In another rarely publicised DWP rule, if a sick or disabled person shares a home with a partner, the fact that their partner earns a wage can be used to rule them out of sickness benefits (the income threshold varies). When I contacted the DWP, it confirmed: “Claims for ESA are assessed against a number of circumstances including living arrangements, income and national insurance contributions.”

That means that people like Denise – who the government are fully aware are too unwell to work – are effectively shut out from social security.

“I put my trust in the DWP,” Denise says. “I wouldn’t have taken a job if I’d known there wasn’t a safety net if I became ill again.”

Since April, with no sickness benefit, Denise’s only income has been her disability living allowance – which she needs to pay for the extra costs that come with bad health. As she puts it: “It’s meant to pay for taxis [to hospital], not bills and food.” But even that’s been cut now: when the government abolished DLA and transferred her to personal independence payments in May, she lost part of her benefit. Now she’s living off just £82.30 a week. “It’s horrific,” she says, and she’s becoming withdrawn and isolated.

When an employer won’t hire you and the state won’t help you, to be sick or disabled simply means having no income

Her partner has a decent wage as a transport contractor – fine for one but not easy to stretch for two – and besides, she says, it’s “awful” when he’s forced to pay for everything. “It’s not like we’re married. We don’t have a joint bank account,” she says. “I don’t like having to say, ‘can I have a money for a haircut, or for tampons?’”

As an insight into just what sick and disabled people are up against, Denise has been trying to find a nursing job this summer – one with less stress – but when she told an employer about her bipolar disorder, a medical report judged her as unfit for work and the job offer was withdrawn. She’s been “scrabbling together” information from the mental health charity Mind to know her rights, and has put in a request to see if the employer will accept changes such as shorter shifts – but if it refuses, she has no way of paying the legal fees to take it to court.

When an employer won’t hire you and the state won’t help you, to be sick or disabled in Britain simply means having no income. Denise has adapted over the years to living on very little – “because I’ve had to”, she explains – but things have never been this bad.

“For anyone to go through this when they’re already ill … just to live, you really think at times like this you’re going to be protected by the government. But you’re not.”