What does a valid Energy Performance Certificate look like?
They are valid for 10 years. Legally they need to be an E rating or above to rent a property unless you have an exemption. You can find more information about the regulations here: https://www.nrla.org.uk/resources/energy-efficiency/energy-performance-certificates-epc
What does a Gas certificate (CP12) look like?
These are carried out annually. You can find more information about the regulations here: https://www.nrla.org.uk/resources/looking-after-your-property/landlords-gas-safety-responsibilities
Electrical Installation Condition Reports
Having a EICR on the property is now a requirement for landlords and they are usually valid for 5 years. You can find more information about the regulations here: https://www.nrla.org.uk/resources/looking-after-your-property/electrical-safety-inspections