Vets would be irresponsible if they let everyone with a few sheep have a bottle of a/bs, irrespective of the person's training and experience. (The press is full of antibiotic resistance scare stories, mostly blaming farmers.).
I would expect the vet of a new sheepkeeper to perhaps be prepared to supply one or two syringes in case of the late night necessity, provided the vet is comfortable that the person would be able to judge when and when not to use it, and has the skill and knowledge to do so. With your background, Dans, I wouldn't have thought that ought to be a problem - assuming you've told the vet you're an expert on fluke!