The education secretary is warned a 'free for all' could emerge after headteachers get the freedom to set their own term dates

The tyranny of the summer school break – an unbroken six weeks of freedom for pupils and inflated holiday costs for their parents – could soon be over, after the Department for Education announces that all schools are to get the power to set their own term dates.

The change is included in the government's deregulation bill, which removes the role of local authorities in fixing the dates of school terms and leaves the decision to school leaders and governors.

However, some school leaders warn that too much variation could lead to chaos for families with children at different schools.

Academies, free schools and voluntary-aided and foundation schools already have the ability to set their teaching hours and term dates. Among those doing so is Boulevard academy in Hull, which plans to reduce its summer break to four weeks. Andy Grace, the headteacher, says the extra two weeks of school will help parents who struggle with childcare for the longer holiday.

The new legislation extends the freedom to all state-maintained schools as the education secretary, Michael Gove, pushes for a rewriting of state teachers' terms and conditions through the independent School Teachers' Review Body.

The change is due to take place from September 2015, affecting the 70% of state primary schools and 30% of state secondaries still under local authority control.

"It is heads and teachers who know their parents and pupils best, not local authorities. So it is right that all schools are free to set their own term dates in the interests of parents and pupils," a spokesman for the Department for Education said.

Under the rules the school year will still have a minimum 190 days of term time. Currently, pupils get six to seven weeks off in the summer, with two weeks at each of Christmas and Easter as well as three week-long half-term breaks.

Brian Lightman, general secretary of the Association of School and College Leaders, said the new timetables could mean difficulties for parents with children at different schools. "Most schools choose to follow the local authority calendar because they know that it's better for parents who have children in different schools and teachers who want their holidays to coincide with their children's," Lightman said.

"The problem will come if no one is responsible for creating a co-ordinated calendar for an area and it turns into a free-for-all. Somebody needs to take the lead locally on deciding term dates and it makes sense for this to be the local authority, even if schools aren't required by law to follow it."

The change was floated earlier in the year by Gove, who complained that "the structure of the school term and the school day was designed at a time when we had an agricultural economy".

The shadow education secretary, Stephen Twigg, last month supported a similar move, saying that all schools should be able to offer longer school terms and extra classes without having to "jump through a series of bureaucratic hoops".