Hi,
Yes, overseas bank interest, is foreign income (SA106) and requires a Self Assessment Tax Return (SA100). You will need to check the guidance at RDR3 and take the residency test, to see if split year treatment applies.
RDR3 Statutory Residence Test
If it does apply, you can only claim split year treatment throug a Self Assessment Tax Return (SA109). The foreign interest will be treated in the same way as UK interest.
Have a look at:
Tax on savings interest
Thank you.