Hi. I haven't owned one but worked in one previously and family member owns one so will give as much info as I can.
Both places were kennels and cattery. A lot of customers had both dogs and cats so was easier for them to come together. Family member also has a small animal care incase customers also have guinea pigs / hamsters etc, but that was set up a few years after they had been up and running
Both places had a washroom. Where I worked, it was attached to the house, like a conservatory type room. It had 2 airers, a giant washing machine and a table. It never had open windows and used to stink.
Family owned one has 2 separate outbuildings. One is a laundry room (2 washing machines, airers and clothes lines you can raise so the blankets are above you) and another is a groom room. Has a giant sink, cupboard full of towels, shower with long flexi handle, clip so dogs can be put on leads and attached to the wall so 2 hands are free for bathing. Medium and tall table for dogs to stand on for grooming. Lots of different brushes and a hairdryer.
No one had any relevant qualifications. The one I worked in had been set up by parents and passed to their son. Family one - both had experience with animals. One was a farmer and one worked for a rescue charity for years.
Where I worked - 10 cat spaces, 35 dog spaces (I think - it was a long time ago). Family one, not sure.
Both places had almost constant maintenance as both were on large pieces of land so fences etc needed tending to. I know family tend to try and do larger projects / upgrades in winter as they are quieter then.
Both said staying on top of the books needed to be done monthly or it was a nightmare job.
Always important to check how your insurance would work (ie what vet would you have to use / how good are they for out of hours / do they cover dogs who have ongoing illness etc).
Both places employed staff. If you don't, you may feel uncomfortable going out as you'd be leaving a lot of people's beloved pets unattended! Also, it can be hard work and long hours if it's just you / you and partner.
Routine when I worked was up, dogs out in turn. While they were out, kennels were cleaned. Once all kennels were clean, dogs were given breakfast / medications. Then exercise, done either in groups or separately depending on what was requested / needed.
A bit of a rest for the dogs while doing some cleaning / washing dog bowls from breakfast. Check everyone has water.
Spend time with dogs giving affection. Walk any dogs which haven't been done yet.
Check diary and make sure you have a plan for tomorrow - who's going home? What time? Do you have kennels ready for any dogs coming in?
Feed dogs tea. Inc any extra medication. Quiet time for dogs while they eat so we could wash dog bowls. Put dogs out in turn. If weather nice, can leave them for longer but need to make sure everyone goes outside.
More affection. Last turn outs and lock up.
In between all this, you need to be answering the phone, arranging the diary, cleaning, washing bedding, booking dogs in and out. In the summer it can exhausting!
O would definitely recommend being quite strict with opening times and being closed for a few hours in the afternoon. People will ask if they can drop a dog off at 4am on the way to the airport or pick up at 10pm on the way home etc. And a few hours in the afternoon means the dogs get to relax without new ones coming in / dogs going out and the noise / excitement that causes. you also get chance to organise dogs for leaving / sporting laundry etc.
Family one baths dogs before they go home if they've been in for a week or more and this has to be fitted in, usually in the afternoon quiet time.
On the other side of this, you can have a very nice life. My family members now work with a few charities and give some kennel spaces for free as 'emergency housing.' They have also gained a pet as one poor owner passed away while the dog was with them.
I would be a little wary if you're not experienced with dogs / their behaviour though. Some are obviously aggressive or become scared and aggressive when somewhere new and that's scary if you've never seen it before. I'm quite good with dogs and have very fast reflexes but even I had a bite from a seemingly relaxed, calm Labrador.