Finding decent, affordable care for school-age children is down to luck for many families, according to a report.
It claims that there is "widespread shortages" in out of school and holiday care, and calls for more attention to be paid to the issue.
The study, published by the Family and Childcare Trust, looked at the current state of childcare for school-age children, drawing on its own surveys, a new poll of parents and an analysis of local council childcare sufficiency assessments.
Local authorities are required to complete these assessments which look at the supply and demand for childcare in an area.
The trust's analysis concluded that across England, Scotland and Wales two fifths (40%) of councils had enough term-time out-of-school care for five to 11-year-olds in all or most of the local authority. In England alone the figure was 38%, in Scotland it was 47% and in Wales it was 45%.
Across all three nations, one in four (25%) had sufficient out-of-school activities for 12 to 14-year-olds in all or most of the authority (27% in England, 28% in Scotland and 5% in Wales) a nd just over a third (35%) of local councils had enough holiday childcare (41% in England, 19% in Scotland and 18% in Wales).
The report adds that research by the Family and Childcare Trust had shown that the average cost in Britain of an after-school club for 15 hours of care is £48.19, and the average price of a week's full-time holiday childcare (50 hours) is £114.51 across Britain.
"For many families whether they find affordable and quality childcare is down to luck," the study says.
A poll conducted with parenting website Netmums for the report found that more than 40% of parents said that their childcare arrangements became more difficult as their children started school, while 63% said they had been forced to change their working patterns to accommodate childcare when their youngster went to school. Nearly 12% of those surveyed said they had quit, or changed their jobs.
"The current out of school childcare system has serious problems when it comes to availability and affordability and in many areas not enough is being done to make things better," the report said.
"Out-of-school childcare needs to be given greater attention by Government and local authorities."
Anand Shukla, chief executive of the Family and Childcare Trust, said: "For many working parents hoping that their childcare struggle ends when their children start school, this damning research shows that unfortunately the opposite is true.
"Far too many parents face a never ending battle to secure affordable, quality childcare just so that they can go to work to provide for their families.
"The system needs a complete overhaul, but in the meantime local authorities must, with the support of Government, implement action plans to tackle the severe lack of childcare for school-age children."
A Welsh Government spokesman said: "This report covers the situation being faced by many parents in England, Scotland as well as in Wales. We recognise that childcare is an important issue for many families in Wales, especially working parents, and will continue to take action on this front.
"We are committed to improving access to affordable childcare and earlier in the year announced another round of funding of £2.3 million for 2014/15 to provide quality, affordable childcare to help families who wish to access childcare before and after the school day.
"We've also launched Building a Brighter Future: Early Years and Childcare Plan which sets our direction of travel with regards to how we provide high-quality early education and childcare for the next 10 years, including in rural and disadvantaged areas. We've just published our first annual report on the plan.
"It's also important to remember that we provide free part time childcare for two to three-year-olds living in our most disadvantaged communities through our Flying Start Programme. More than 31,000 children in Wales benefited from Flying Start services last year."
A Department for Education spokeswoman said: " Childcare is a key issue for parents. That's why as part of our plan for childcare we're committed to driving up the choice, quality and flexibility of provision.
"As a result 64% of primaries are now providing care before school and 70% after, and after 12 years of rising prices the cost of childcare in England is actually falling in real terms.
"But we want to go further. That's why, next year, we'll be introducing tax free childcare, providing 1.9 million families with up to £2,000 of support per child."
A Scottish Government spokesman said: "The Scottish Government is committed to improving and increasing high-quality, flexible early learning and childcare that is accessible and affordable for all children and families, and which matches the best in Europe.
"This report highlights that Scotland is delivering more than the other parts of the UK on term- time out-of-school care for children aged five to 11.
"The Children and Young People (Scotland) Act 2014 has introduced a duty on local authorities to consult locally on out-of-school care which will broaden the scope of consultation and planning beyond early learning and childcare in order to meet the needs of all families.
"We are also working to help support Scotland's families through funding work designed to promote flexible and family-friendly working."
Reacting to the figures, 4Children, a charity running children's centres across the country, has called for more political support for integrated family support services.
Anne Longfield, 4Children's chief executive said: " Families need out-of-school services that are holistic, robust and flexible enough to manage their childcare requirements. As part of a staged move towards a universal childcare guarantee, there needs be a guarantee of 8am to 6pm childcare for four to 14-year-olds in and around schools.
"A network of childcare and extended community hubs, based in and around children's centres also needs to be developed. These hubs could co-ordinate childcare in every area to help parents find the flexible support they want at the times they need it."