With regard to the rules for importation i suggest you speak to your vet or Trading Standards office , who will be able to give you the appropriate Ministry contact number. No doubt the Ministry office would give you all the required information re paperwork , blood tests etc that would be appropriate. They should also have names of people who have gone through this process before . Not sure if data protection would allow them to give too many details or not of such individuals.Certainly pigs have been imported to the AI centre at Deerpark before.
Hope thats a start for you at least, and good luck.