So we 'pretty much' ended up with our original idea. And by 'pretty much' I mean, the tiler still stuffed up and incorrectly tiled our niche with the hexagonal tile.
Instead of ripping it down, because obviously it would cost them, our SS sent us photos and asked if we'd be happy to keep it this way.
I much preferred this over our original idea; which was to tile the niche with the same square tile covering that back wall. This way, the niche ties in with the splashback. So we were rather quite happy with the error :)