Harvey Greener

My wife and I bought a property in UK in August 2004 for 110,000 pounds. We lived in the property until August 2010 and then moved abroad and rented the property until September 2023. We sold the property on 15th March 2024 for 176,000 pounds. We owed 26,000 pounds on the mortgage and paid 6000 pounds in fees to sell it. We therefore had 144,000 paid into our bank account. We now need to pay Capital Gains Tax. My questions are: Do myself and my wife submit two separate CGT returns and when we input the values we halve everything e.g. house bought for 55,000, house sold for 88,000 etc? Can I use my own valuation of the house in April 2015 (based on similar houses sold in the near vicinity in that year) or does it have to be an official valuation? If there is an official valuation needed where do I get this from? Are you able to give me an estimate of what we would pay?