When renting out a property it is your responsibility to maintain it in line with the terms of the tenancy agreement. If you breach these terms and there are health and safety problems, your local authority could take action against you.
To help ensure your property is safe, it is a requirement that you install a smoke detector, it is also advisable that you install a carbon monoxide detector. It is your responsibility as a landlord to install these however it is up to the tenant to maintain them while they are in the property. Obviously when a new tenant moves in, you need to check they are working correctly.
If there are any gas appliances in the property it is a legal requirement to have an annual check carried out by a Gas Safe registered engineer. Once this check is complete and all appliances deemed safe you will be given a gas safety certificate. You must provide your tenant with this certificate within 28 days of it being issued.
You also need to provide an Energy Performance Certificate, this shows how energy efficient the property is and is to be provided whenever the property is let to a new tenant.
Although not a legal requirement, it would be advisable to have the electricity installations and electrical equipment checked. This would ensure that everything was in working order and is safe.