Out of a red-brick shop front in Manchester’s Moss Side, the Greater Manchester Law Centre is set to fight for a piece of the welfare state. John Nicholson – a local barrister and chair of the GMLC – puts it like this: “We’re not just a law centre. We’re a campaign for justice.”

To understand exactly how one small, volunteer-run law centre is launching a fightback against the government – and with it, what it represents for towns and cities up and down the country – we have to go back almost four years, to the spring of 2013. This was when the legal aid budget was gutted by £350m a year. Overnight, a cancer patient found “fit for work” or a cleaner sacked for falling pregnant was priced out of the legal system.

At the same time, local councils feeling the squeeze of austerity began to pull funding from welfare rights services, debt advice centres and law centres. In a matter of years, face-to-face expert advice largely turned into a helpline or a website. “As if you can just send people – vulnerable people – away with a form,” Nicholson says. “Lots of people don’t even have access to a computer.” There used to be nine law centres across Greater Manchester. Now there are two. Only Rochdale and Bury’s survive.

Nicholson is 62 and has lived in the area since he was a teenager. He’s watched his local Citizens Advice shut its doors, and the wider region become what he calls “a desert for legal advice”. Neighbouring Salford’s welfare rights and debt advice services was cut four years ago. When the South Manchester Law Centre closed in 2014 – the last free legal service in central Manchester and Salford – for Nicholson and others in the community, it was the final straw, and the impetus to do something. They had no funds or premises, but within a year they’d built up enough support to found the GMLC: a place where anyone can go for help.

It is run entirely by volunteers: experts like Nicholson giving up their time, trade union workers and law students from all five nearby universities (“the next generation of social welfare lawyers”, as Nicholson calls them). The focus is currently on employment and welfare rights: the two areas hit worst by legal aid cuts. “You’ve seen ‘I, Daniel Blake’?” Nicholson asks. “We’re the people representing Daniel at tribunal.”

Talk to Nicholson and that’s what stands out about all this. It isn’t only that the government has pulled funding from legal aid or welfare advice centres, but that it did so at the same time as it brought in policies (such as fit for work tests and cuts to council tax support) that mean these services are needed more than ever. We could call it the definition of a rigged system. The bedroom tax hits you and there’s probably no debt service to turn to. Or the jobcentre sanctions your benefits but the local welfare rights centre that would have helped you to appeal has shut.

The result, Nicholson says, is that people feel as if they’re going crazy. “No one will answer your phone call or help you. You can’t understand why they’ve brought in this housing regulation or benefit rule. You think it must be you that’s wrong.”

The GMLC doesn’t officially open until Saturday, but Nicholson and his team have been representing the community since September, with 200 cases in the first three months. Many of them are disabled people wrongly found “fit for work”. People started turning up as soon as they heard the centre was coming, knocking on the doors with plastic bags full of paperwork.

“They’re desperate,” Nicholson says. “Some people are desperate because they’re broke. Some people are desperate because they’re being evicted. But lots of people are desperate because they’ve got nowhere to go.”

Across the country the picture is disturbingly similar, from the Law For All charity in Ealing, west London and Leeds’ asylum seeker service, which have both already closed, to west Norfolk’s disability service – run by disabled people and their carers – currently having to crowdsource to stay afloat because it’s funding has been cut.

In Moss Side, Nicholson is already looking for more volunteers to staff the centre. A colleague in Brighton told him of a mother and baby who were recently “put out on the streets” after losing their home, and he’s worried mass evictions will soon hit the north-west. There’s only a scrap of legal aid for housing rights left, and new cuts like the benefit cap and housing rent cap are on their way. “We’re not letting the government off the hook,” Nicholson says.