Yes, you will need to register for self assessment, as you are in receipt of overseas income, regardless of how little it may be. Interest from overseas bank accounts, is taxed in the same way as UK interest.
Please have a look at the guidance below and take the residency tests.
RDR3 Statutory Residence Test
This will help you determine whether all of the interst is taxable or just the proportion arising from when you came to the UK, to the end of the tax year.