Good news: at last, my voice has returned!! After 4 days of complete silence and a further 2 of sounding like an alien with a voice box, things are finally back to normal (or as normal as it gets).
On this detail from the rough, you can see what it will read when finished:
I scanned a sample of my textured pastel paper into the computer to create an identical 'virtual' paper. I can then draw onto this, in 'virtual pastels', using Corel Painter, and get the exact same texture as the original drawing: