Low-income families are still struggling to find good quality, flexible childcare, according to a new report.
It reveals that, despite Government financial support for pre-school education, practical problems such as a lack of evening care and inflexible hours are still a barrier for parents who want to work.
At the same time, many mothers and father are reporting that the cost of childcare is stopping them, or their other half, from increasing their working hours or accepting a job.
Under the current system, all three and four-year-olds in England are entitled to 15 hours of free nursery education or childcare each week, and this is being extended to the most disadvantaged two-year-olds.
But the new report, published by Citizens Advice, says that many parents are struggling to find suitable and affordable care, with the options available to low-income families and those working evenings, weekends and unreliable hours "considerably narrower" and often involving a compromise on quality.
It found that 75% of childcare providers did not offer evening or weekend care, and more than half (57%) needed a notice period of a month or more to change care arrangements.
The better the Ofsted rating a childcare provider holds, the more notice they required to change childcare arrangements, the report says.
Just under 80% of the best providers wanted a notice period of a month or more, compared to just over 50% of those with poorer ratings.
The study, based on research carried out by Citizens Advice bureaux, including 400 surveys of childcare providers, also found that nearly half (46%) of childminders did not offer the Government's free early education hours.
It concludes that finding suitable childcare that fits around working hours and financial circumstances is "not a straightforward task".
"Many studies have shown that working outside of a '9 to 5' full time job in the UK is not unusual," the study says.
"Parents who work in low income jobs like social care, retail and hospitality are also less likely to have control and choice over their working hours including working outside of standard hours and working to shift patterns."
"Whilst evenings and weekends work patterns are more common for lower income jobs, childcare provision which offers extended hours is typically less available and of lower quality."
Around two fifths (41%) of Citizens Advice's clients say the cost of childcare prevents them or their partner from working more hours or taking a job, the charity said.
It added that parents are also having to shell out money upfront, with 90% of nurseries and childminders asking for payment in advance, and 40% requiring a deposit of up to £150.
"Parents on low incomes have even less choice in the childcare market and less control over their hours because they are more likely to have unsecure contracts, to work evenings or weekends, and to find that their shifts change from one week to the next," the report says.
"As a result too many children, particularly those from disadvantaged backgrounds, are missing out on the higher quality early education that they need to get on in life."
Gillian Guy, chief executive of Citizens Advice, said: "Our evidence shows that the most suitable childcare options for those on unstable hours are likely to be of poorer quality, which could have a damaging impact on a child's ability to learn and develop. Parents who work shifts or irregular hours may find that the lack of availability will be a major block to getting work. A last minute change of shift or an unexpected meeting could mean parents see their hard work undone by extra costs.
"Upfront costs are a hurdle for families trying to make ends meet, and for many it will simply not be possible to scrape together a deposit and advance payment to hold down a place for their child. If parents are unable to access or afford decent childcare then they can be prevented from going out to work. Government has made excellent progress in helping with costs but everyday childcare is at odds with modern working Britain."
A Department for Education spokesman said: " We agree that parents deserve more flexibility and choice. That is why we are giving all three and four year olds, and the most disadvantaged two year olds 15 hours of free childcare a week, which all parents are able to use flexibly. We are also cutting red tape, encouraging new providers to enter the system and making it easier for school nurseries to open longer.
"We are also pleased that the report has recognised our strong financial help for parents. After 12 years of consistently rising prices, costs in England have stabilised for the first time - in fact once inflation is taken into account costs for the majority have actually fallen."