The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 has not been made law, however, the regulations have been presented to Parliament and subject to Royal Assent, are due to come into force on the 10th October 2015.

Landlords will be required to install smoke detectors on every floor of the rental property and ensure they are tested at the beginning of each tenancy.
Carbon Monoxide Detectors must also be installed. Any landlord failing to comply could face a penalty of up to £5,000.00
Landlords and letting agents (that includes estate agents & property management companies), should prepare properties pre- October to ensure that they comply.
Inventory clerks should also ensure they are up to speed on how the new regulations affect their day to day role.