We have just bought a derelict property with a gas aga. It not a boiler also, but this info might be useful:
My 1st problem was finding someone experienced and qualified for agas and gas (likely the same for rayburn). Not all gas trained people are qualified for cookers, and not all aga/rayburn people can touch gas, as its a separate certificate apparently! I'm in the Sth East, near reasonably sized towns, and not rural, but had difficulty finding someone to come to see if it was even worth keeping. Either they weren't gas qualified or didn't travel to where we live! I literally called 8 people and found 1, so might be worth ringing around now, to see IF someone in your area cover gas rayburns.
There is also a thriving 2nd hand market, so if you do decide you don't want it, you could sell it. Whether you sell it yourself, or have a specialist dismantle it first, its up to you. We are adding an extension, so had ours dismantled, and will be put into the new kitchen. I read alot about costs, heating etc. My gas is about 2p/kW whereas electric is 17p/kW, so a gas rayburn is currently the cheapest fuel to use if you do keep it.
I'm yet to actually use the aga, but plan to have a separate oven also. Apparently with modern insulation, more and more people have theirs turned off over the summer now, because it can be too hot. I've also found that rayburns and agas seem to be like marmite- people either love or hate them! best of luck whatever you do.