UK resident, sold property in Europe. What documents I need to prove value?

Hi, I'm a European national but I have lived in the UK for the past 10 years and I am a resident here for tax purposes. I have never owned a property in the UK but I own a property in my native country that I am in a process of selling. I know that I don't need to pay tax in Europe as it is considered my only property, but I will need to pay capital gains tax here in the UK as I am planning to transfer the funds of the sale to my UK account. The property was given to me by my uncle in 2016 - in nature it was a gift, but at that time it wasn't possible to form a gifting contract, so we went ahead with a standard property sales contract, where I paid my uncle 100 euros. This was of course just a formality of the contract. I don't have any information on the property value in 2016, but I have just done a property valuation and I have official proof that the property now at the time of my sale is worth 30,000 euros and I am going to sell it for a value close to that. I haven't done any improvements on the property and I am selling it just as I received it. What is the proof needed to submit my self assessment? I am concerned that I don't have any property valuation information from 2016, so I can't at the moment estimate my true "gain". What is the paperwork needed to support this?

Hi
You will need to contact an estate agent abroad for them to give you a valuation based on similar properties that were sold at the time you received it. This will then be your purchase price. a copy of said valuation would need to be privded as evidence for your figures.