You seem to have done loads of research so far and I think you are definitely on the right path . I would say that you shouldn't right off using electric fencing, as pigs soon learn no to go near it and it stops them weakening fences. A barb wire strand at ground level deters them from grubbing under the fence, and one on top deters climbers, both piggy and human. 150 sqm seems adequate for keeping two weaners through to finish, the more overgrown the better. Your local council environmental health dept, and defra will be pleased to help you with advice on the red tape. Your right to plan ahead for the pigs departure, they are strong and willful at 6 months, and can make a little noise but not excessive. piglets can be carried, but 150kg porkers need to be walked into a trailer. ther are lots of pig ark types about, you just choose the one that suits yor budget and long term plans. you could easily make one out off recycled components, ie old hd ply sheeting from building sites, bolted together in a tent shape, with a door at one end and a vent at the other. using old sleepers as batons across the base,as a guide, will give you a decent size for two or three pigs( @ 8 x 6 feet). the pigs can also use this as shelter from sun and rain , but do love it if they have got somewhere to hide and to wallow. Also before you start do you know where they will be ending up? abbatoir, butcher, customers etc. welfare wise , have you considered what they will eat and where you will get it from, and store it. water supply?and also is there a vet locally who has experience of pigs? How will you feel once you have put all this effort in and you have to take them to meet their demise? have you considered only keeping them for five months, by which time they should be quite big enough, @ seven months old.From experience I must warn you that you will love these pigs and the only way to get over them going is to get more. Good luck and I hope you enjoy the experience.