Hi L-I Am,
If you work abroad as a crown servant (HM Armed Forces, civil servants or diplomats) you pay Income Tax in the UK on income from your job for the Crown as if you live in the UK.
The rules apply regardless of your UK residency status for tax, no matter how long you’re abroad, where you work or how settled you are.
This means that you would continue to complete your tax return as normal, using the standard HMRC online version.
Have a look here for some more information:
Tax for crown servants, EU employees and volunteer workers abroad
Thank you.