Hi,
If you were not UK resident in the tax year in which the property was disposed of, then you do not need to report the disposal to HMRC.
If you were resident in the UK in the tax year in which the property was disposed of, then you will need to declare the disposal in a Self Assessment tax return. You will need to work out if there was a capital gain, using UK rules, which can be found here:
Capital Gains Tax
Thank you.