Hi,
You will need to confirm if you your service contract is a contract of employment or whether it is an agreement allowing you to provide a service to your client. You can use the tool below to help you determine if you are employed or self employed:
Check employment status for tax
Foreign employment income is declared on SA102 and foreign self employment income on SA103. If you are required to pay foreign tax on either source of income, this is declared on SA106 and a foreign tax credit claimed.
Thank you.