Mr Miliband will use a speech at the North of England education conference in Warrington to reveal that unions are close to signing up to historic contractual changes and a redefinition of teachers' roles.
The one cloud on the horizon for the Government, however, remains opposition by the National Union of Teachers, which objects to the use of teaching assistants to take classes.
The TES understands that the NUT is being told it will be excluded from future talks on introducing more support staff into schools, should it refuse to back the Government's plans in principle.
Mr Miliband has been talking for the past three months with employers'
representatives and unions representing teachers, heads and support workers. On the table have been contractual changes including guaranteeing all teachers 10 per cent of their timetabled time away from lessons for marking and preparation, a limit on the time teachers spend covering for absent colleagues, and a redefinition of the roles of support staff.
Although the NUT's opposition to the use of teaching assistants to cover for absent teachers is well-known, Mr Miliband was hoping that all the other parties would agree verbally to the proposals before Christmas.
They refused, but all have promised to put the proposals to meetings of their executive committees this month. All except the NUT are likely to back the Government.
Mr McAvoy said: "There are key sticking points about the balance of support staff in schools."
Shadow education secretary Damian Green will use the conference to unveil Conservative plans to give schools fresh powers to opt out of services provided by their local education authority.
The move will be seen as a virtual reinstatement of grant-maintained status, and represents a ditching of William Hague's "free schools" policy, which would have scrapped local authorities. Under the new proposals, put forward by a working party of Conservative councillors, schools could choose whether or not they opted out.
Meanwhile, in his conference speech, Liberal Democrat education spokesman Phil Willis will attack Labour for creating a "Fordian production line" system of education, dominated by league tables, which is letting down the 50 per cent of pupils who fail to gain five good GCSEs.
He will set out his party's vision: no league tables, national tests at seven, 11 and 14 and no GCSEs. Instead, there will be far greater emphasis on the learning needs of individual pupils.