Hi harryss53,
SA100 (tax return) page TR3, boxes 1 and 2 are for UK interest.
Provided your overseas interest is not taxed and is below £2000, you can declare this in box 3.
If your overseas interest is more that £2000 or has tax deducted from it, you would declare this on supplementary page
Self Assessment: Foreign (SA106)
Tax Return (2023) if you are using the online tax return, you will need to tailor your return to include foreign income if the criteria for showing the interst on SA106 applies.
Thank you.