Hi,
So I've used the casting creme in mahogany before, but that was before the grey kicked in. It looked quite nice after a few washes, but was initially too dark. I'm very pale and yeah...not a good look.
I also tried the Iced chocolate one, which is probably more subtle. Possibly too subtle, but given my main objective now is covering the grey, subItle is probably ok.
I've thought about mixing the two, but I've never done this before, so don't know how easy that is to do.
Any other recommendations? My hair is quite dry and heat damaged, so something conditioning is definitely essential.
I really don't want to start dying my hair now, as I know that will be it. I'll need to commit, as I just wouldn't suit grey. Plus I'm only 34.
I should add, I'm heading at the door very shortly to Boots, so please post your suggestions quickly! 
TIA