My 2p worth:
Buildings insurance is higher for a listed and thatched building - ours is £1.2k a year.
Thatch isn’t more likely to catch fire, the issue is that once it’s ON fire there’s not much anyone can do - think about it, it’s supposed to repel rainwater, so a fire hose isn’t going to help if it’s on fire and there’s an abundance of fuel eg more thatch! A fireman locally told me they can’t do much except rescue people and things but they often spray water to appease onlookers and to be seen to be doing something.
However, if you follow safety precautions eg getting the chimney swept twice a year, never leaving a fire overnight etc it’s fine. A real fire is lovely. Our roof has been intact for 300+ years so...
Listing applies to the whole building but you can decorate without permission except eg you can’t paint the front door sky blue if it was putty coloured. Realistically though councils don’t have the resources to check unless it’s flagrant or reported.
I’d want to see listed building consent for that extension IIWY.
That thatch looks in good condition but it’s expensive to replace. We’ve been quoted from £45k - £55k but it’s a bigger roof than your house. If it won’t need doing for 25 years don’t worry. Get a thatchers opinion though before buying.
I don’t care about ghosts but feel privileged to live in an old house. We have flagstones and servants bells and love our house, which we’ve lived in for over 10 years. We’ve spent £££ on decorating but the maintenance has been fine, apart from the thatch. The PP who said don’t worry about minor points is right but do get a full survey from someone who knows old buildings. I don’t regret our house as it’s an amazing family home.
That said, I’m not sure I’d do thatch again but that’s because ours needs replacing! Good luck.