Good directions, Patricia. I would add, though, Paddy, that you may want what's called an "header" at the top. This will help keep the sun from filtering through that space between the rod and the wall. If you follow Patricia's instructions, simply make the header 1 or 1.5 inches. I would also allow 1.5 inches for a rod pocket. That's just the rule of thumb in the industry for these size rods.
Have you ever thought about roman shades, Paddy? That's what I'm going to have made for my Lovebug. In fact, I'm going to do two layers, an outer layer of just what you described, rod pocket top, center split, holdbacks with another sheer roman shade behind this to filter out the sun and give privacy without blocking out the sun totally.
Another thing to consider is that you can purchase "block out" lining which is wonderful for insulating any drapery. This is available in different weights and you do want one that is suitable for the fabric you choose. It does add bulk, but, it's wonderful in keeping out the heat or the warmth in.
Pictures when you're done!