Unless you are going to employ staff, you will not be able to make anything near £50k.
Ime, dog boarding in your own home, is what there is most demand for. If you do this, you can't really offer walking as well, because who would look after the dogs you have at home?
You will need a Dog Boarding licence from the council (£96 per annum) and pet sitting insurance. Cliverton is the best, and costs £110 per annum.
The council will decide how many dogs you can board. Most people have a licence for 2, I have a licence for 4. I charge £20 a night for boarding. On a good day, I will be full and have a couple of daycare in as well, in which case I would earn £100 + a day. However, there will be days where you earn nothing or a small amount. It can be seasonal, so earning more in summer, for eg.
I would highly recommend screening the dogs - have them stay for 1 night before you let them stay for 2 weeks! Some dogs are absolute horrors. I have had dogs :
- chew furniture
- eat my shoes/slippers
- eat money
- crap and pee inside (cream carpet!)
- Howl from 3am onwards (meaning you have to get up for the day)
- attack me (thankfully only one dog)
- eat all my plants in the garden
- dig up all the grass
- slip collars and run away (found)
- jump on to my desk and knock everything flying
- smash ornaments
- scoop everything out of the bin and eat the contents
I could go on....
You have to weed these dogs out. I use post-it notes to mark their records, after their stay, to say whether to take again.
Some owners can be frustrating as well. For eg. saying they will drop their dog off at 9.30am, and then appear on your doorstep at 7.30am, before you're even dressed! Or say they will collect their dog at 4pm, and by 7pm, still haven't shown up and not answering their phone. Meanwhile, your dinner is burning....
I'm now 4 years in. The first 3 years were REALLY hard work. I have now weeded out all of the difficult dogs, and can honestly say that my life is wonderful. The dogs that I take, display none of the above bad behaviours. I take them out around 10.30am, get back at Noon, have some lunch, and then the afternoon is really relaxing, as they sleep and I can watch a bit of TV, do some admin (bookings etc), put a wash on, tidy up, read a paper, go on MN etc. They wake again about 4pm and at 5pm it's time for their dinner and another walk.
Great to have no boss, no targets etc. Decide your own holidays (as many as you want a year).
Hope this helps!