Hi 4740 Wong,
If you are resident in the UK and have an overseas bank account, you will need to declare the interst to HMRC, in a self assessment tax return. Please also have a look at the tax treaty that exists with Jersey:
2018 Jersey -UK Double Taxation Agreement – in force)
To determine if your interest is also taxable in Jersey.
If it is, you can claim a Foreign Tax Credit of up to 100% of the foreign tax paid.
Thank you.