Ii need advice about what sort of tradesperson(s) I need for my job(s)

1. I need a new 4-ring gas hob installed to replace a failed one. I have the new hob ready to go, but it will apparently require some additional pipework to connect to the gas supply, so that would need to be sourced by the tradesperson(s). 2. Since the old hob had developed a fault, an emergency British Gas engineer also capped the gas at the meter until it could be replaced, so apparently need a "gas-safe" engineer to uncap it once the new hob is installed.