Lost property acquisition costs for calculating CGT

We have lost the details/amounts of the acquisition costs incurred when we bought a flat in Dec 2005. Does HMRC have or allow indicative acquisition costs - property survey and legal fees? If so can you advise what these would be/point me in the right direction please. Thanks

Hi,
You can use reasonable estimates but you must refer to this in your computation.  If your computation includes estimated figures 
or a valuation, you must tell us:
 • where and why you’ve used estimated amounts
 •  how you worked out these amounts
For valuations, you should also include:
 • the date of the valuation
 •  a full description of the asset 
Thank you.