Everything on a call is diagnosis and guidance. Any hands-on gas work must be carried out by a Gas Safe registered engineer, and any notifiable electrical work by a qualified electrician. I'll tell you clearly when you've reached that point.
Smell gas, or hear your CO alarm?
Don't book a call. Leave the property, then ring the National Gas Emergency Service on 0800 111 999. In Northern Ireland it's 0800 002 001.
Power cut, or a damaged cable or substation outside?
Ring 105. It's free, 24 hours, and puts you straight through to your local network operator. Most people don't know it exists.
Burning smell, sparking, or scorch marks indoors?
That's not a power cut. Turn the circuit off at the consumer unit if it's safe to do so, and get an electrician out. If there's fire or anyone's in danger, ring 999.