Working parents face bills of about £800 for childcare over the summer holiday, according to research that shows provision remains inadequate across the UK, particularly for disabled children whose families struggle to find appropriate care.

The annual survey by the Coram Family and Childcare children’s charity suggests a postcode lottery of holiday childcare in terms of cost and availability.

Provision has improved slightly on last year, though some families continue to be harder hit than others. Fewer than one in five local authorities (17%) in England say they have sufficient holiday childcare to meet the needs of children with special educational needs and disabilities in their area. Older children, aged 12-14, and those living in rural areas are similarly poorly served.

The survey shows prices have risen by 3% in Britain since last summer, meaning parents pay on average £138 for one week of holiday childcare – double what they pay for after-school clubs during term time. England is the most expensive (£140), followed by Wales (£130) and Scotland (£123).

Costs are highest in south-east England where parents pay on average £162 per week per child – up 10% on last year’s prices – 37% more than in the north-west, where childcare costs are cheapest at £119. In the south-west, the second most expensive region, costs have gone up 20% to £154.

Coram said low income families would be severely affected by holiday childcare costs, especially those who rely on universal credit which is paid in arrears. Parents will have to find money to cover childcare costs up front, potentially pushing many into debt.

Parents working atypical hours also face severe shortages in provision, with only 14% of local authorities reporting enough childcare for this group, though nearly half of councils did not know or did not collect data for this group.

Megan Jarvie, the head of Coram Family and Childcare, said: “Working families are being left with few options this summer. The high price and low availability of childcare means that many struggle to stay in work, or can end up paying to work. Families need to see urgent action to fill the gaps in availability and financial support.”

Sarah, a mother of three from south-east London, who has a son with autism and ADHD, said she was unable to work because she could not find suitable and affordable childcare over the summer.

Holiday schemes are too stressful for her son because of the lack of routine, she said. “A childminder would have to know him very well to be able to manage his needs and it is difficult to find this kind of provision in the short-term.”

Christine, from Lewisham, south London, who has recently gone from full-time to part-time work, said: “Holiday childcare is too expensive and there is not enough of it. This has had a real impact on our family life over the summer because I have had to split my holidays with my partner to make sure that one of us is available to take care of our child.

“As a result, we are not able to spend as much time together as a family as we would like. And even then, our annual leave never covers all the holidays and does not include the inset days.”

Anntoinette Bramble, chair of the Local Government Association’s children and young people board, said: “Reductions in government grants mean councils find it increasingly difficult to provide their own childcare schemes, but are working closely with their communities and providers to support families in need of holiday childcare.”

The survey is in its 15th year and is based on information supplied by family information services at local authorities in England, Scotland and Wales, as well as freedom of information requests. The childcare described includes Ofsted-registered holiday clubs managed by the private, voluntary and independent sectors as well as those run by local authorities.