Hi,
The disposal of the Italian property should be declared in a self assessement tax return. Under the terms of Self Assessment, we do not provide an official exchange rate and the onus is on the individual to use a just and reasonable exchange rate for each acquisition and disposal.
For your convenience, there are exchange rates at:
National Archives: Exchange rates from HMRC in CSV and XML format
For older rates, please see:
National Archives: Foreign exchange rates and spot rates: 1 January 1989 to 31 March 2010
You are free to use any of the supplied rates or one of your own choosing.
To help you work out the capital gain, there is a calculator at:
Tax when you sell property
Guidance on private residence relief can be found at:
HS283 Private Residence Relief (2024)
Thank you.