I would think that it will be near impossible to find "grazing" for pigs. Very few landowners would be prepared to rectify the mess pigs will make of it.... Sorry if his sounds patronising, but after last summer when most fields were trashed even by sheep it wil become even more difficult. If you can keep small numbers of pigs on land you own you would probably be best to keep the herd small and stay there.
Easier for sheep, and cattle, but again where you are near to Edinburgh small parcels will probably be "gazumped" by horse owners also desperate and often more fluid in the cash department....