However if you intend to light a fire in there , that's different as you will need a heat resistant material and as such that's not so common and a different question....in the image you post I'd guess those are actual bricks,,,
It will have a log burner. Do you still need special tiles/brick? No joy in topps- theirs are too big or not slim enough. Tried a couple on independent tile merchants up north - no luck either. The need to be relatively small and slim given its for a fireplace.