All private landlords have a legal obligation to ensure that the tenants they rent to have a right to be in the UK.
These checks are called Right to Rent checks and most landlords will apply this to all tenants applying for their property even if they are a UK national. A landlord will ask you to provide a form of ID such as a passport. If you don’t have a passport they can accept other documents such as birth certificate or driving licence, but you will need to provide two of these.
The landlord will need to take a copy of these and keep a copy on their records.