Heffers,
Forget the fireplace; more than 40% of the heat goes up the chimney spout anyway. We had our wood burning stove installed last year.
1) calculate the volume of the area you want to heat. On the web there are sites that will convert this value into Kilowatts require to heat that area.
2) get a chimney sweep to clean out the chimney.
3) have a chimney soundness test made to check for leaks.
4) Buy the appropiate stove (gas, wood, coal or combined wood and coal) correct to the Kilowatt outage value required.
5) Get the supplier to install it himself or suggest an approved installer for you. Make sure the installer puts in a chimney liner (very expensive - £900=$1800, but safest option) and insulates it.
Light stove, sit as snug as a bug all winter. Most efficient way to heat your living room/house.
Ours is only 4 kW and boy does it kick out some heat.