The headteacher of a comprehensive in Philip Hammond’s constituency has expressed disappointment at the chancellor’s budget suggestion that a bonus for schools could pay for “little extras”, months after she outlined to him the financial crisis her school was facing.

Earlier this year Katie Moore, the principal of Fullbrook school, a mixed secondary in Hammond’s Surrey constituency of Runnymede and Weybridge, became so concerned about the impact of funding cuts that she wrote to him asking to attend his surgery.

He offered to visit the school in New Haw, near Woking, and in May he spent an hour and a quarter looking around while Moore explained the funding problems faced by Fullbrook, which has 1,500 pupils aged 11-18.

She told him she could not afford to pay teachers enough to meet the cost of living in the home counties, class sizes were growing and schools were having problems meeting the requirements of young people with mental health issues and special educational needs.

“I was delighted to welcome Mr Hammond, our local MP, to Fullbrook in May this year when he gave generously of his time and listened carefully to our experiences including the impact of funding cuts,” Moore said.

Then on Monday, after announcing a £400m one-off payment to schools in his budget, Hammond sparked outrage among teachers and parents when he airily suggested the money was “to help schools buy the little extras they need” – a whiteboard or a couple of computers, he later elaborated – seemingly oblivious to the scale of their need.

The payment will provide £10,000 for every primary school in England, and £50,000 for every secondary. According to the National Education Union, it is a drop in the ocean as schools face a £2bn funding shortfall a year.

Moore, who has worked at Fullbrook for 13 years and has been principal for two, welcomed the additional money, which she said would help with refurbishments (the school is carrying out roof repairs after a flood in the main corridor) and extra IT.

“We were pleased that there’s been recognition that something needs to be done in schools. But when the money was described as for little extras, I felt very saddened, particularly given that Mr Hammond had visited our school. It showed there was a misunderstanding about what it is that schools need,” she said.

“This does not even scratch the surface to meet the current funding pressures that schools are experiencing. He saw on his visit to Fullbrook that we are desperate for enough money to support the basics of our students’ curriculum and the fundamentals of a good education, not just what he described as ‘little extras’.

“We need an increase to ongoing core funding that addresses the cost of teachers and support staff. We need to close the funding gap left by the 8% real-terms cuts over the last five years that schools in his constituency and around the country are unable to meet.”

Hammond explained in subsequent interviews that school funding would be dealt with in next year’s spending review. “We put £1.3bn of additional money into schools funding last year to protect per-pupil spending in our schools,” he said.

The £400m bonus had nothing to do with that process, Hammond said. “It was simply giving back a little bit of the money that we’ve saved this year so that schools can buy the odd little piece of kit that they need. I think that’s a nice gesture.”