A quarter of UK voters have started taking precautions against the adverse consequences of a no-deal Brexit, including stockpiling food, toiletries and medicines, according to a new Opinium/Observer poll.

While 75% of those questioned said they had taken no special action, the remaining 25% said they had taken one or more of a series of measures listed by Opinium, which also included altering travel plans and delaying major purchases.

The survey was taken after leaks of official documents showed concerns within Whitehall about the effects of no deal on the supply of food, medicines and other items.

Among those who had taken action, 9% said they had begun stockpiling goods, 8% said that they had delayed major purchases and 7% said they had altered travel plans. Among people who said they had begun stockpiling 57% said they bought extra tinned food, 45% extra medicines, 38% more toiletries and 30% additional toilet paper.

Local authorities are having to spend millions of pounds on social work agencies as they struggle to recruit permanent staff, with some authorities employing nearly half of their children’s social workers through private companies, a Guardian investigation has found.

Data obtained through freedom of information requests shows that many English councils are routinely spending tens of millions of pounds – a total of at least £335m in 2017/18 – hiring agency social workers.

Experts said the difficulty experienced by councils in attracting permanent staff meant vulnerable children and families were often seeing multiple social workers in a single year, making it harder for them to engage with services.

They said the large-scale use of agency social workers was a poor use of dwindling local authority funds, as locums received a higher hourly rate than permanent staff, on top of the fee paid to the company they were employed through.

The government has failed for the sixth time to hit its own deadline to publish details of care system reforms for adults with disabilities and the elderly, because of the Brexit gridlock wracking the Commons.

Charities claimed lives were being put at risk by minsters’ “dithering and delays” and warned vulnerable people denied care, such as those with learning disabilities, were at increased “risk of abuse and neglect”.

Health secretary Matt Hancock told MPs in January that he “intends [to publish] before April” the social care green paper containing the government’s plans to make care safer and financially sustainable.

On Friday the Department of Health and Social Care told the The Independent it had no plans to publish the document before Monday 1 April.

Age UK said this was now the sixth time ministers’ assurances have fallen flat since the originally scheduled publication date of summer 2017 was missed.

Social services for older and disabled people face crisis because post-Brexit migration restrictions could cause a massive shortage of care workers, leading care organisations have said.

The 1.4-million-strong UK care sector’s reliance on European migrant workers means it is vital they are given the right to remain in any future migration arrangements, the charities Independent Age and the International Longevity Centre UK (ILC-UK) said.

Currently about 84,000 care workers – equivalent to one in 20 of England’s growing care workforce – are from European Economic Area countries. About 90% do not have British citizenship and their future immigration status remains uncertain.