I’ve used 2 catteries before, one of them sent my cat back a nervous wreck and the other I use regularly because my cats love it! The one I wouldn’t use again was very a much a ‘business’ - it was very well equipped, lots of staff and immaculatey kept, but it was very clinical and different people every day, and the lack of continuity really unsettled one of my cats. It also meant that no time was spent with them outside of feeding and cleaning so they didn’t notice that one of my cats was loosing a ton of weight and was miserable.
The Cattery that I use a lot is run by a lovely woman who treats the cats like her own pets and it’s almost a continuation of her own house. There’s arm chairs and a log stove in the indoor Cattery area and the cats can have a roam around when their pens are being cleaned. There’s only 2 members of staff so the cats get to know them and they spend loads of time being fussed and spoilt.
I’ve no idea about the regulations side of it, but I’d say that the best catteries and kennels aren’t the ones that have been set up as a money making business. The best are the ones that have come about because the owners are obsessed with animals and want to spend all day playing with kittens 
Keeping it small and almost hobby like will give the cats the best experience, and keep the owners coming back.
Also, have double doors on all the entrances - a Cattery I know of years ago lost a cat because someone opened the external door when a pen door was open. It could have been avoided if they had a porch area or similar! The first thing I checked when looking for a new Cattery was what the security was like.