Hi CapitalGainTax,
You only have 4 years from the end of the tax year in which the loss arises, to claim losses.
Unfortunately, you are too late to do this.
Please have a look at the guidance at CG15250:
CG15250 - Expenditure: incidental costs of acquisition and disposal
You would need to be able to provide evidence of your allowable fees in one format or another, if HMRC asked for this.
Thank you.