Two possibilities:
1. Father signs site over to daughter in sole name. Avails of exemption from CGT and stamp duty if first such transfer and daughter intends to build ppr on site ( other terms and conditions apply, ask your legal advisor). No gift tax- well within threshold ( assuming no prior gifts or inheritances from either parent).
2. Father signs site over to daughter and son in law. No exemption available. Stamp duty on site, CGT and gift tax on half transferred to son in law. AMounts depend on exact value of site.
Now only reason to put in joint names is if bank insist for mortgage purposes. If that is the case, first transfer into your wifes name and she then transfers into your joint names. Only problem will be that you will still be caught for gift tax on half the value of the site ( less the relevant threshold) but at least no stamp duty or CGT.
Or wait ( is it 3 ) years and then no gift tax on transfer into joint names.