Foreign currency - USD/GBP

Hi there I am an UK resident starting from 23/24 tax year. Before 5/4/2023 I had had some USD and I changed part of it to be GBP in October 2023 for expenses, savings and investment in UK. 1. Shall I take the (HMRC) exchange rate of USD/GBP in April 2023 against the actual rate I got in October 2023 to calculate the gains or loss? 2. Based on the purpose (expenses, savings and investment in UK), shall I report this gains or loss? 3. If I shall report this, where shall I put this figure in the tax return? Thanks.

Hi T Yeung
Currency other than sterling is a chargeable asset and its disposal can give rise to a chargeable gain or an allowable loss, but Capital Gains Tax on foreign currency depends on the situation.
Capital gains arising on withdrawals of money from a foreign currency bank account will not be liabile to Capital Gains Tax.
It stands to reason that capital losses would not be allowed.
Please have a look at the guidance here:
CG78300 onwards.
CG78300 - Foreign currency: introduction
Thank you.