Hi K,
You will need to review the guidance at RDR3 (
RDR3: Statutory Residence Test (SRT) notes) and take the statutory residence tests. As August 2023 to April 2024 will be more than 183 days, you will be tax resident in the UK for the whole tax year. You will need to considre whether split year treatment applies. If it does, you only declare your world wide income from the date you arrived in the UK until the end of the tax year. If split year treatment does not apply, you will need to declare your worldwide income for the whole tax year and claim any foreign tax credits for tax paid overseas. The Hong Kong / Uk tax treaty allows for your employment income derived while living and working in Hong Kong to only be taxed in Hong Kong. This would include the bonus payment made, when you had moved to the UK.
Thank you.