If the country where you earn income has a double tax agreement (or similar) with your home country, you might be able to just submit your tax return in the UK as normal, listing only any income earned in your home country (eg interest in bank account, any rent income from a house etc). The agreement basically says that the two countries accept that the other country can tax their citizen on earnings there (abroad), and the home country will not apply further taxes on that money when it is brought back (to the home country).
If the country where you earn income has a double tax agreement (or similar) with your home country, you might be able to just submit your tax return in the UK as normal, listing only any income earned in your home country (eg interest in bank account, any rent income from a house etc). The agreement basically says that the two countries accept that the other country can tax their citizen on earnings there (abroad), and the home country will not apply further taxes on that money when it is brought back (to the home country).