Hi jayp555
Yes. All UK dividends and bank/ building society interest, should be declared on the self assesment tax return, as they arise in the UK.
By completing the SA109, to declare that you are not resident, these sources of income will be included in your self assessment calculation, as disregarded income.
Self assessment system will make two calculations, one with the disregarded income and one without.
The lower tax liability of the two will then be your tax liability and any tax above this amount can be repaid to you.
Please take a look at the helpsheet HS300
Non-residents savings and investment income (Self Assessment helpsheet HS300).
Thank you