How much grazing does a miniature horse/ shetland need?

[cutelilpony]

Hi, I was thinking about rehoming a rescue mini or shetland. I have a small paddock which is around 1/2 acre, would that be enough? I can build a stable if nescessary. They would be kept as a companion but I was considering doing a bit of natural horsemanship training so they would get excersised also. The grass in the paddock is quite long and there is no shortage.

I would also like a breakdown of costs per year in Ireland (they on't need tack and probably won't be shod). I am only working part-time as a student so I wouldn't like to buy the poor thing if I can't afford it on my small wage

Thanks a mil!!