So after filling a few skips so far and being told "no plasterboard", the penny only dropped that this might be difficult stuff to get rid of at the plastering stage.
We have quite a large house so generated quite a bit of scrap, especially the rooms in roof where there are lots of triangular sections. Turns out that the local skip firm will do a plasterboard only skip but at an increased cost to normal to cover the additional landfill cost.
I got a 4.5 yd for £265 inc VAT (Berkshire) and it was just big enough (note to self, always get a skip one size larger than you think you need). Quite tricky to fill it efficiency too, I ended up stacking larger bits up the sides and kept the middle for small bits, which I regularly compacted with a sledge.
I did call a few of the industry recycling schemes but they're only geared up for big sites.
A few skip companies go by weight but the challenge of keeping a skip of board dry put me off, not paying to dispose of rain water
Note that there's no issue in disposing of plaster itself in a normal skip, we've accumulated quite a few bags of scraps and will have quite a few more before we're done.