Hi Peter Maddocks,
If you gift a property to your son, you may have Capital Gains Tax to pay from that gift.
Please have a look at the guidance here:
Tax when you sell property
Which includes a calculator to help you work out your gain and tax payable on it and guidance on reporting an paying the Capital Gains Tax.
You must report and pay Capital Gains Tax on UK property within 60 days of the completion date.
Thank you.