Thanks to everyone for the quick replies – i really appreciate it

  I will be using an accountant when the time comes, but i was just trying to do some 'high level' calcs in anticipation of next years Tax Return.  

Terry W, would an Agents market appraisal be sufficient at time of sale? (the family member wll not be applying for finance so wont be getting a val done) – cheers

All these replies have helped me so thankyou all