Parents say a school uniform recycling programme is a "lifesaver" as they face paying hundreds to kit out their children for the start of term.
Beneficiaries of a community clothing hub in Kent said they would otherwise face paying large lump sums to buy school uniform - money that "could be spent on other things".
A poll by The Children's Society found 41% of parents in the South East struggle to afford mandatory uniforms, while some families choose between food and clothing.
Rebekah, who cares for her granddaughter after her daughter's death, took the bus from Canterbury to the Community Wardrobe in Whitstable. She said: "It's really tough to go through everything they need for school."
Gabriel, another parent at the community wardrobe, added: "I'm here because I don't want to go to the official outfitters and spend £150 which I don't really have."
The Children's Society said 44% of parents said they had experienced negative consequences related to sourcing school uniforms.
The charity added that 3,000 parents said they were being unfairly punished or excluded because they could not afford expensive uniform, much of which is paid for in one lump sum before the start of the school year.
Sara Beadle, from the school uniform charity Stripey Stork, based in Reigate, Surrey, said: "We hear about parents who are looking at going into more debt than they are already in or having to make difficult decisions between food and clothing, or heating and eating.
"It's not a situation we want families to be in."
The Community Wardrobe in St Alphege Church in Whitstable said it had seen an increase in demand for pre-worn school uniform as parents sought cost-effective solutions.
Isobel Legg, who coordinates the project, said: "We have had some lovely comments with loads of people saying it's a lifesaver.
"It just helps people so much."
A limit of three items of branded primary school uniform, with four items for secondary schools, is set to be enforced from the start of the 2026/27 school year in a bid to give families more freedom.
Education Secretary Bridget Phillipson said: "School uniform matters, but it shouldn't break the bank. No family should have to choose between putting food on the table and buying a new blazer.
"Schools can help ease the pressure on families right now by reducing the number of branded items they require."