Is it just a butcher you are looking for, or an abattoir too?
We use Shotts for our sheep. I think I have seen pigs there, but I'm not sure. Worth asking. Otherwise I think it's a trip further south but I can't remember which abattoir. There are folk locally who have to take their pigs there, and it is a trek. Sad that Gala is closed as they did pigs, wild boar too.
For a butcher, Jim Cairns in Law village is excellent - knowledgeable, and he cuts exactly how you want, makes sausages and burgers, and he collects from Shotts too.