Hi and welcome. You should always keep at least 2 pigs, as they are very sociable animals. Ideally they should be sent off together so that one is not left alone to pine.
Theoretically you could keep pigs on an area that small, although I doubt the quality of meat would be much more than the usual supermarket stuff. The cost of compensatory feeding would make it prohibitive, without a Colditz type fence you would be unlikely to keep them in such a small area. Within a couple of weeks it would resemble either the Somme or the Gobi desert dependent on weather. If you have neighbours you would be inundated with complaints, quickly followed by Public Health Inspectors. If DEFRA gave you a holding number for pigs for such a small area.
This does not read like much of a welcome but to encourage you into keeping pigs in such an area would be contradictory to the ethos of this site.
On the other hand if its not too dark and damp chickens would be a good source of protein as meat and eggs.