As mentioned above, if there is a financial tenancy deposit, you must do this through the tenancy deposit scheme - one used to be free if they held the deposit, another one you kept the deposit but paid an insurance to cover the tenants deposit. https://www.gov.uk/deposit-protection-schemes-and-landlords/overview
Electrics are supposed to be safety checked.
Annual gas check is compulsory.
You need landlords insurance.
If it is an HMO you need more things like 5 year eleccy certificate. If its a large HMO there are more requirements and has to be licensed by the council.