We moved into a new house last year, and the previous owner had converted the garage into a cattery. I'd like to make them kennels and do them up. Ideally I'd like it if they could pass a council inspection for the breeding licence in case I ever needed one in the future rather then redoing them later, but at the moment they will mainly just be used for storage and if a friend wants to stay with their dogs so it doesn't really matter.

I've got 7 pens in total, the sides are half wall half mesh with wooden frames. I'm thinking tileing the walls.

Any tips or ideas I should look into with them?

Have you  checked the licencing requirements regarding the kennel size?
I was shocked that each kennel would need to be 12m2 for a pair of dogs or 8m2 for an individual. I can't remember off the top of my head, but I think it was 16m2 for a bitch with pups. I'm not sure how big your garage is, but my kennel had to be 12 x 4m for 3 pens (6 non breeding dogs). 
All wood surface would need to be sealed/covered and some drainage would need to be installed to wash the kennels out.