Capital gain of main residence by married couple

An overseas property, which is the main residence of a married couple living there for over 10 years, was sold after becoming UK resident with capital gain. (1) Can entitle for PRR in this case, am I correct? (2) May I know whether the married couple could be treated as single entity and the CGT could be shared when reporting if only one of them is the owner in the legal document but both of them (i.e. the married couple) are the “borrower” for the mortgage in the legal document? (3) If yes, may I know the percentage of capital gain to be shared between this married couple? (4) If shared, how to indicate the shared portion of capital gain in our individual self assessment, as we need to report the original purchase price and disposal price in full (minus the solicitor fee, agency fee, etc) to calculate the capital gain but this will be in full capital gain amount?

Hi,
The disposal needs to be worked out in pounds sterling, using exchange rates applicable at the time of acquisition and disposal. As the property was the main residence, Private Residence Relief can be claimed for the period that it was the main residence. This may cover any gain, so no tax is payable. You can see guidance here:  HS283 Private Residence Relief (2024) 
There is also a calculator below to help work out if there is a gain:
Tax when you sell your home
The disposal should be declared on a Self Assessment tax return. Under the terms of Self Assessment, we do not provide an official exchange rate and the onus is on the individual to use a just and reasonable exchange rate for each acquisition and disposal.  For your convenience, there are exchange rates here:
Exchange rates from HMRC in CSV and XML format
and for older rates here:
Foreign exchange rates and spot rates: 1 January 1989 to 31 March 2009
You are free to use any of the supplied rates or one of your own choosing.
Thank you.