Hi,
A UK resident individual is required to declare their world-wide income and gains to HMRC each tax year. An individual with overseas income or gains would do this by completing a Self Assessment Tax Return, no matter how small the amount of overseas income or gains and even if no tax is payable.
You would declare your overseas income and or gains in pounds sterling, by submitting SA100 (tax return) and any supplementary pages as appropriate. Overseas interest would be declare in pounds sterling on on SA106 (foreign).
You can register for self assessment at:
Check how to register for Self Assessment
Thank you.