Read this slowly line by line.
I will start with the conclusion just so you do not get confused. You absolutely need buildings insurance.
1) Your house burns down and does not damage anyone else's
Your insurance company will fix the problem.
2) Your house burns down and damages your neighbour's house
You will be liable for the damage done to their house.
Your insurance company will pay for the damage done to their house
3) Your neighbour's house burns down and damages your house
3A) Neither of you have any insurance
You can claim off your neighbour but they probably won't be able to compensate you.
3B) Your neighbour has insurance but you don't.
You can claim off your neigjbour and their insurance company will compensate you
3C) You have insurance but your neighbour doesn't.
Your insurance company will compensate you and may go after your neighbour
3D) You both have insurance.
Your insurance company will compensate you and then discuss the matter with the other insurance company.
In all cases, you are better off with your own insurance.