So you earn at least £230,660 (based on your claim of paying 90k tax, possibly more - you say you pay that much ) and you had to take your child out of a fee paying school?
HM Treasury's latest tax-summary methodology puts education at 10.3% of public spending.
So that means you pay £90,000 is 10.3% of your tax bill, then:
£90,000 ÷ 10.3% = £873,786
So your total tax bill would be about £873,786.
If you're saying £90,000 is the amount of your tax that effectively goes toward education, based on the 10.3% public-spending share, then you'd need to be paying about £873,786 in total tax for 10.3% of it to equal £90,000.
For England/Wales/Northern Ireland, ignoring pension contributions and other reliefs, you'd need approximately:
£2.06 million a year
At that salary, roughly:
Gross salary: £2,060,000
Income Tax: ~£873,000
National Insurance: ~£41,000
Take-home after Income Tax + NI: ~£1.15 million
Average Income Tax rate:
~42.4%
So I dont think you meant that at all