You need to measure the size of the room so you know what size woodburner you need, you can put the numbers into
this online calculator also see the considerations on that page for a better clue.
If you're in a smokeless zone (or other planning restrictions) this will limit the type of stove you can fit.
You can get also some good advice from a good stove/woodburner shop, who should give some clues as to regs, what you need flue wise, and costs.
Do you have a chimney already? If so it'll probably need a liner, size depending on the stove, may also need a register plate. Otherwise you can use stainless steel twinwall, expect to pay over a grand for twinwall flue. Either is easy enough to fit yourself once you're familiar with the regs which are all available online, twinwall is as easy as leggo, just clips together, how high you need it depends on the situation, the regs explain it pretty well, maybe look at installation instructions for a particular stove, and/or particular flue manufacturer like
Selkirk or
Poujoulat.
DIY is OK but you'll need it tested & signed off by a HETAS engineer if you don't want to invalidate insurance.
to give you a clue on costs, I've fitted two different stoves in our place, cheapest stove was £400, the twinwall flue for that was £1200 with 45% selfbuilders discount straight from the wholesalers

expect to pay more if someone else is installing it
Pumpy