Roof’s in Rupert are notoriously short lived due due to wind and rain. And I suspect the problems are not limited to old homes!!
Depending on where the leak is, it may simply be a matter of getting up there with some roof patch material… but be warned it can be tricky finding the source of the leak. I was lucky with the last leak I dealt with… flashing by the chimney was noticeably the source.
As for mice… yeah they seem to enjoy warm dry accomodations as well. My suggestion is to stick with old fashioned traps until your cats get their mouser instincts going. Take a look around the house to see if there are obvious spots where the mice can come in from outdoors. Amazing how small a crevice they can squeeze through. Caulk cracks or stuff them with steel wool.
We tried pellets that we were told would dry out the mice after eating and they would seek sources of water outside … worked like a hot damn… except years later during renovations… I discoverd dried out meese carcasses in the ceiling… thus the advice to use the old fashioned traps… disgusting to clean out but at least you know they are gone.
Hopefully the mice will decide not to chance living where cats are living and they will move out shortly!!! Good Luck…