Ian Trafford, head of Benhurst primary has earmarked pound;27,000 for three part-time teachers and an extra 15 hours of assistant time each week to allow teachers half a day off for marking and lesson-planning from September.
The money has come from pound;57,000 of savings accrued over five years from careful management of the school budget.
Mr Trafford said: "We have a very small computer suite. Only half a class can use it at a time. The new suite would have allowed whole classes to go in."
Mr Trafford anticipates that the rest of the savings will be spent on PPA time in the second year. After that he does now know how he will be able to afford it.
Jason Clark, who has a son in Year 2 at the school and is chair of the parent-teachers' association, said: "To watch all those savings slip away is sad. More worrying is that there is only so much money put aside. Is the school going to go into the red in two years?"
Mr Trafford will also scrap one and a half days of relief time for subject managers, something inspectors praised the school for.
Benhurst has just received a pound;1 million share of money Havering council raised from the sale of Gobians school, but Mr Trafford says this will be spent on replacing two temporary classrooms with permanent buildings and renovating the dilapidated canteen.
Havering LEA is providing pound;2.5 million above what the Department for Education and Skills is contributing to cover PPA time An NUT spokeswoman said: "The pupils, parents and teachers of Benhurst will be extremely disappointed that a move that would have helped the teachers is being delayed because of the Government's stinginess."
A government spokesman said schools, working with the national remodelling team, should be able to fulfil the PPA requirements.