If you are not resident in the UK for tax purposes and you are in receipt of income from savings and investments, then this income is condiered to be 'disregarded income'. This means that while it is not taxable, any tax paid on this income is not refundable. Have a look at HS300 for more information on this.
HS300 Non-residents and investment income (2023)
As a non resident individual with UK income, you would need to submit a self assessment tax return, declaraing that you are not UK resident and the amounts of UK savings and investments you are in receipt of.