Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
Firstly, when you left last February did you both complete a Form P85 and send it to HMRC? If you did not you should do so immediately. Fortunately there is no time limit as to its submission, it is available on the web and can be filed on line. On receipt HMRC will classify you as non resident. On your return you should tell HMRC and they will split your return year into two portions, one non resident and the other resident.
You will not be subject to UK tax on any gain made on the sale of your house as Private Residence Relief (PRR) would apply in any event. However, you should warn your UK bank of incoming funds and their source to preclude any money laundering inquiry a large transfer might otherwise attract.
I do hope that you have found my reply of assistance. My reply does not include any NZ taxation liabilities. However NZ does not have a capital gains tax regime save for certain specific investments.
Thank you for your support.
My daughter lives in NZ and works for the NZ government.