Offsetting Losses in Conjunction With Property Sale

I am in the process of separation from my partner, note we are not married. As part of the separation, I wish to sign over to him a property that is in my name, which attracts a capital gain. From what I understand I am required to declare and settle the payment for the gain within 3 months. I would however like to offset that against a capital I loss I have incurred when making an overseas investment (a loan to a company that has failed to return the any capital or interest). Can anybody help with understanding how I do that? I do not have the cashflow to fund the capital gain payment now and then recoup the credit in a later year...I would like to declare the loss in combination with declaring the gain from the property sale.

Hi Mark Arnold,
There is a Capital G Taxains calculator here:
Tax when you sell your home
One of the questions in the calculator will ask if you are claiming Capital Gains Tax losses from tax years before 2023 to 2024 that you have already reported to HMRC. You will need to enter the losses in this box, even if they occured in 2023 to 2024.  
When completing the Gapital Gains Tax online form, there will be a section for in-year losses.  
The losses would be declared there.
Please note that you have 60 days from the completion date to report and pay any Capital Gains Tax.
Thank you.