First, ask the school immediately. Explain the change in family finances and ask both about a deposit refund and any bursary, hardship or discretionary fee support. Some schools will help, especially if the child has already been offered a place, but it depends entirely on their terms and budget.
On the deposit, check the acceptance form and terms very carefully. In many independent schools the deposit is not automatically refundable if you withdraw, but some terms do allow refund in limited cancellation windows.
On VAT, there usually is not a simple SEND exemption just because a child has ASD or ADHD. Since 1 January 2025, private school fees are generally subject to 20% VAT. The main exception is if the child has an EHCP and the local authority names an independent school because it is necessary to meet need. In that situation the local authority pays, and VAT would not usually be added in the same way to parental fees because it is not a private fee-paying placement. So one practical question is whether this child already has an EHCP, or whether an EHCP assessment should be pursued now. Without one, private-school SEND funding is much harder to unlock.
Well also worth going back to the grandparents and asking whether they can stretch a bit, even to around 40 to 42 percent, because that may save the whole plan. Sometimes a smaller increase feels more manageable than “half”.
Ask the school whether fees can be staged, whether extras can be removed, and whether there are scholarships, bursaries, sibling funds, hardship funds or temporary support for the first year.
If the numbers still do not work, I would not rush straight to home education unless you genuinely want that. A mainstream state secondary with a strong SEND reputation, good SENCO, small nurture provision and proper support plan may be a better option than an unaffordable private place.
I would move quickly, because bursary pots and waiting lists tend to move fast.
my kid has asd and adhd good luck to you