I want to change my leaking gas fire back to a coal/log fire as i like the look of old fires. The chimney was originally for a coal fire as next door but one still has a coal fire. Would a liner or something have been put up the chimney for the gas fire or would it still be open as for coal? The gas pipework is cut off so i guess i can remove the fire without any gas problems. Who would be best to call to check the chimney out, gas man, builder, chimney sweep?After a sweep has been done i guess a smoke test would have to be done- by the chimney sweep? I have a marble hearth and back plate with a polished wood mantle, would this be ok for an open fire or would i need to change it?