In this situation, you will need to work out the amount of foreign credit you can claim. When asked "Do you agree the amount of foreign tax credit relief shown above?", select yes (for the time being) and save and continue. Move on to view and print your calculation. Have a look at the calculation, to obtain the amount of UK Capital Gains Tax payable. If the UK Capital Gains Tax is more than the Overseas Captial Gains Tax, then the foreign tax credit is 100% of the overseas tax paid.
If the UK Capital Gains Tax is less than the overseas tax paid, then the foreign tax credit is the amount equal to the UK tax payable. Click on back to take you back to the "Capital gains - foreign tax credit relief and Special Withholding Tax". Change the radial button to 'No' and now enter the amount of tax credit you are entitled to claim. Click on save and continue to go back to your calculation, which should now show the credit.