Where both Case 5 and Case 8 apply, the case that takes priority is the one with the earliest 'split year' date.
In your particular case, that would be Case 5, with the starting date of the UK year as 23 July 2022.
And yes, you would be required to complete a 2023 Self Assesment Tax return to declare the Foreign Interest arising between 23 July 2022 and 5 April 2023.
RDRM12030 - Residence: The SRT: Split year treatment: When will split year treatment apply
Tax on foreign income