The message from David contains these words:
Not sure what you mean by "having the living room floor done."
What sort of floor is it now? What are you doing to it? What's underneath it at the moment?
There's many a suspended wooden floor is sitting just a few inches above damp bare earth.
If that's the case, and it's a wooden floor that's being repaired or replaced with similar, then make sure that at the very least the bare earth is covered with dpm which is well weighed down. And preferably that there's a few inches of concrete laid on top of that. Plenty of opportunity to put in an air feed for your fire then.
An underfloor draught to your fire will reduce the need for your fire to take in combustion air from the room and so cause major draughts.
If you have an open fire, however, the "draw" (suction effect) of the chimney will still take some of the air from the room up the chimeny and ensure a significant amount of ventilation.
Keep a check on your relative humidity in the different rooms of the house. Hygrometers are dirt cheap -- if you don't want to buy a proper one, Lidl seem to be forever offering clocks with built-in hygrometers for three or four pounds. If your Relative Humidity is higher than 80% your house is far too damp. Should be in the region of 30% to 60%. Get a decent dehumidifier if it's over 70% . I prefer to have models with a built-in heater to ensure they work efficiently.