If the property was in your name when this was sold, then you may be subject to Capital Gains Tax on this if you are UK resident. There is no Income Tax due on the transfer of money itself.
You can find further guidance on Capital Gains here:
Capital Gains Tax
If you have already paid Capital Gains Tax on this in Greece, then you can advise us of this and claim for foreign tax credit relief so you are not taxed twice on the same income.
This would be done through Self Assessment.
Self Assessment tax returns