Are you going to Maddocks in Maesteg? If so, don't just speak to Gill, who does the bookings - ask to speak to Collwyn. He'll be the one you meet when you offload your pigs and he has a much better idea about what they can offer re. butchery. Also, there's a retail butcher's shop on site, so you can speak directly to the butchers - but be warned, the older one can be a bit miserable and short with you!
Saying that, though, a very good abattoir as far as slaughter is concerned. I just wouldn't choose them for butchering. And their sausages are really bland, btw. Did two test batches from the same pigs - one batch made by them, another batch made by another butcher. No comparison.