We have three moggies that are all kept indoors as we live near a very busy main road. What we have done is to come off of our conservatory with a "cat tunnel" this runs for 23' down to their cat house and run. Their house has heating and lighting so they are perfectly happy. Having a cat house and run in your garden allows your cats to have the best of both worlds without any of the dangers of roaming free.
Grange Pet Centre