Never had a gas outage. Electrical outages common. Gas fire place used as an emergency back up several times. Reface the fireplace easy DIY job. High heat paint for the metal trim. Will need a pipe fitter that has gas ticket to decommission the gas line. Termination holes exist that need to be filled in the foundation/siding etc... Will need an electrician to decommission the electrical. You will be left with an electrical cover plate on the wall or terminate with an outlet? Chimney, where is it? Does it run up the outside of the house past the roof or through it? The latter is probably as expensive as what either tradesman is going to charge.