Heptavac needs two doses, 4-6 weeks apart, to be effective - then an annual booster. On another post, some members say they never use it and haven't had any problems. Personally, I'd use it but the choice is yours.
With your sheep, I wouldn't routinely worm. I would do a faecal worm egg count in spring and autumn and worm if required. If your land was clean ie free of sheep for a year or more and you can rotate the grazing, you might never need to worm. Adult sheep build a resistance to worms.
Fluke is a bit more complicated and your vet is probably best able to advise on the fluke issues in your area. Faecal testing isn't reliable for fluke. If you vet advises fluking, he may be able to give you enough for four sheep - ours does.
I wouldn't have thought that you need to vaccinate for anything else, especially if you aren't breeding