So... Made my own rub from what I had in the spice cupboard; equal parts onion powder, paprika, garlic powder, brown sugar and 1:2 of cayenne pepper and mild chilli powder and coated it good an proper on Saturday night. Left overnight to let the spices sink in.
On Sunday morning at 9.30am I put it in the (fan) oven at 125°C and roasted for 6 hours. I don't have a digi-probe, so I used the kitchen meat thermometer stuck into the end of the joint, running parallel to the bone. Not sure how accurate either the oven or meat thermometer temps are, but after 6 hours the meat was showing well above the 'Pork' temp on its dial. Tried it in a couple more areas of the joint and they were all reading over (it states 77°C for pork, I'm sure I've read different on here for pulled). Looking at the wide end of the bone I could see the meat starting to lift from it a bit.
Once out of the oven I foiled it, taking care to keep the juices that had seeped out, wrapped it in a towel and put it in a cool bag, leaving it to rest for another hour.
When it came to pulling it was slightly more difficult than I'd imagined it should be, although the meat was pretty tender. It didn't fall off the bone, but the bone was pretty clean once I'd stripped the meat off. Mixed up the meat with a little Sweet Baby Ray's Honey Barbecue Sauce and served with white buns and coleslaw (not home made, that's next).
Family enjoyed it hugely, getting our kids to eat anything other than chicken can be a challenge, but they wolfed it down. I've got a feeling it could have been better though, although I was very pleased for a first attempt.
Any pointers on things I could do to improve? Apart from build the UDS of course.

