Right, I've done it! I did it this morning. Product arrived yesterday having ordered it on the weekend so very quick service.
In the end I decided against using a curling wand to do it curly, as I love the wand I got but I was worried I'd not get the ends quite right so I decided to do it straight with GHD's then go through it and curl it at the end.
So I shampooed twice with the clarifying shampoo, towel dried, blow dried to total dryness, applied the product in sections combing it through, then blow dried that (it dried much quicker and less heavy than I thought it would like everyone says - you just don't quite believe it till you do it!). I then straightened it very thorougly in sections, going over 7 times, at that point I still hadn't decided whether to just have it straight or curl it, but then thought, sod it, I'm never going to wear my hair straight, not tied up, not tucked behind ears etc etc for 3 days, I have 2 young children and the hair is like a scarf I'll be sweltering, so I curled it with my GHD's into lovely glossy waves, and I have clipped it up away from my neck just very loosely.
What I am hoping is that when I wash it out on Saturday (or even Sunday if I can wait) it will dry with a bit of wave and nice and soft and shiny. Worst case scenario is the waves/curls dont "hold" but I should still have the conditioning effects of the treatment. Whilst my hair still looks fine, it feels a little dry and brittle as I've done lots of naughty things to it so I'm hoping it might replenish some of the protein bonds and improve the condition so I can do yet more naughty stuff to it in future! 
Will report back when I've washed it in 3 days!