Any income you earned or gains that arise before 6 April 2023 will not be taxable in the UK.
There is a possibility that your income/gains arising from 6 April 2023 to July when you arrive in the UK, may be taxable in the UK.
To find out if this is the case, you will need to review your residence position and whether split year treatment applies.
Have a look at :
Residence, domicile and the remittance basis: RDR1
and then the statutory residence tests at:
RDR3 Statutory Residence Test