Hi,
Your self employment income will become taxable in the country that you relocate to and in the UK, up to the date you leave the UK.
You will need to consider the rules on split year treatment to see if they apply in your circumstces. Please have a look at the guidance at RDR3 abd take the tests here:
RDR3 Statutory Residence Test
You will need to complete a Self Assessment tax return, regardless of the outcome of the tests.
Thank you.