Your expectations and the landowner's requirements may not match, so your own work, checking out several places, will be necessary. You'll need land with grass, suitable for grazing, a proper supply of water, and fencing suitable for ponies. There should be a gate that actually works.
You'll need to think about the presence of other horses nearby. If your horses get out, where will they go?
Additionally - - - Ponies live on air, and will founder on fat air. You do not want other people, out of the ignorant goodness of their hearts, feeding anything to your ponies. Maybe some sort of sign, DO NOT TRY TO FEED US ANYTHING . Or perhaps, following A A Milne's description of Piglet's house, TRESPASSERS W.