Few comments
- the gather is key to a good open fire. The dimensions are set out in the building regulations but best for a HETAS installer to do it / sort the flue
- I think you're bonkers - log burners are waaaay more efficient than open fires. Every log you cut, trasnport and split I hope you'll remeber this bit... you are doing TWICE as much as you would have needed for the log burner
- Morso stoves are decent, make sure you sell it on
- The surround is also worthy of being preserved if you don't intend to keep it in place
- When not lit you have a massive hole in your house letting heat out. Nice in summer but you're letting your heat pump heated air out the top of the house for no reason. At the very minimum, get a chimney sheep (thing that blocks most of the flue), but on an evening after you go to bed, from around 2am onwards you are losing heat and money until you wake up the next day and reblock the chimney. Utter madness.
- open fires emit more pollution that log burners, especially the newer DEFRA approved ones. You may not care much about the lungs of others but it's worth mentioning for anyone else reading. Being in the countryside doesn't mean much in the UK, as you're never far from others. I don't disagree with biomass heating / fireplaces in principle, but open fires are unfortunately definitely worse
Edit -
More than unfashionable, burning stuff that pollutes the air for others and covers the houses and gardens of neighbours in ash and soot is probably one of the most antisocial things you can do in a domestic setting these days
There should be a strive to ban most forms of small scale combustion outright; leave it to larger well engineered processes that will scrub the output to minimise its harmful effects
Going down this line of thinking we should be banning BBQs, garden waste fires, chimineas, gas hobs and so on. They're all more polluting than a fireplace. Also, fireplaces tend to only be lit when everyone else is inside with the doors and windows closed, whereas the other big sources of pollution (vehicles) operate all day everyday with exhausts at lung height. So I would think the particulate matter from a fireplace lit in winter is far less likely to reach a lung than from a diesel engine operating in a town.
