Wide range of answers and advice, some sound, some not so sound.
To cover your points as they arose;
The installation of a stove comes under Building Control Regulation. While it is perfectly legal to install your own stove it must then be signed off as safe to use prior to use by a qualified building inspector. Not getting is signed off means that you are in breach of building regs, you could then be fined several K. If you then have a house fire it is highly likely that your insurer will invalidate any insurance cover.
The building regulations appertaining to stove installation can be downloaded for free here:
https://www.planningportal.gov.uk/buildingregulations/approveddocuments/partj/approved.
You will need fully insulated pipe to go through the ceiling/floors, this is usually shiny stainless steel but we usually powder coat to match the colour of the stove. You will need a fire stop plate on the floor of the bedroom, the pipe is this room must be boxed in as it presents a serious fire hazard if anything comes within its combustible distance. How far that is varies between pipe manufacturers, I use Poujoulat and its 50mm, cheaper less well insulated brands are more than that, some a lot more. Don't forget the floor joists are combustible.
How much heat output do you need?. You have just said a stove, work out the volume of the room you wish to heat and divide by 12 if you have poor insulation, 14 for average and 16 for good.
So, a good quality stove that will take long logs, my recommendations for a short list would be,
5kw, Esse 100, either single or double door. Nordpies Bergan
8kw. Esse 200, either single or double door, Morso Panther, Morso 08.
Above 8kw most stoves are able to take a long log.
I do act for Villager and saw that someone had a door sealing issue, there is usually no sealing strip between the two doors. The doors themselves are all hand fitted to each stove, this involves hand fettling and the use of a 'vibratic persauder' (a hammer !!) problems of that nature not that I have ever had any need referring to Villager for their engineer to sort. I have serviced and repaired Villagers over 30 years old that have simply needed new firebricks and not a lot else. I have never come across a leak between the doors.
Someone was talking about burning old fence posts, as long as they are not creosoted then that's fine. Avoid creosoted ones like the plague unless you want a chimney fire.
Hope that helps.
A