Sheep need other sheep. We always say get at least 3, then if one dies the remaining sheep still have another sheep for company.
Not sure whether pygmy goats eat grass, regular goats are browsers rather than grazers, so will eat shrubs and so on but not really grass.
Some people say that if you have goats and sheep, to keep them on separate ground, or worm control becomes difficult. Other people run goats and sheep together!
Two-thirds of an acre isn't much for sheep the size of Ryelands, even without the goats. If you still want sheep, I would look into a much smaller breed, like the Ouessant or the Soay. Three of those might manage on your 2/3 acre.