Hahaha, I was looking at the book last night, trying to figure out material lengths etc, and I realised just how big a job it all was! So I've changed it a bit for now - I'm just gonna make one sheer curtain (to be closed all the time) that slips onto the curtain rod, and a lace curtain that can either be pulled back or left shut, depending on light requirements. It's still gonna look better than what's already there, and there's a higher probability that I won't stuff it up!

Thank you so much everyone for your help - apparently I've given out too many rep points in the last 24 hours, but I'll get back to you!