Sorry to hear about your sheep. Maybe the leg was actually broken? Even so, I would have expected a bit more promptness from a vet.
We have a local vet who only deals with dogs, cats, rabbits etc. We are fortunate to have a large animal practice just a couple of miles from us. Although two of my neighbours use horse vets at different practices, both 20 plus miles away, and they are happy to come out, for a mileage charge of course.
Ideally, you need a vet as close as possible, who is able to come out quickly, for cases such as you have just experienced with your sheep.
Do hope you find a good large animal vet nearby.