The UK deducts tax on the arising basis. This means that if the charge from the councile arose in 2020 to 2021 tax year, then the full cost of the repair should be shown in 2021 to 2022 tax return.
On SA105 (2021) the full £4000 Roof repairs would be shown in box 25 "Property repaid and maintenance". Should a loss arise, there is guidance at:
HS227 Losses (2021)
Please note that the last date to amend 2020 to 2021 tax return is 31 January 2023. If it is too late to amend the tax return, then an overpayment relief claim can be made instead.
Guidance on how to make an overpayment releif claim can be found at:
SACM12150 - Overpayment relief: Form of claims