Thanks for all your replies. I think you're right TiffinGirls, there's very little room for error nowadays - bad news for the future fatbananas as the scores are increasing year on year.
Tiffinboys I was wondering what papers are harder than GL? I'm interested as I may be going down this route again in future (sucker for punishment me!) and I think I'd start earlier with GL and then move onto these harder papers.
I don't think the multiple choice format suited my DC, as it was too easy to just pick an answer rather than working it out systematically - this was our problem both at home with practice papers and clearly in the exam too. He would fly through the answer sheets - tick tick tick - there was always something else he'd rather be doing than those papers! (...and I can't say I blame him!) I think a standard format would have suited him better, forcing him to put his brain in gear and work things out from the start.
Well done to your DC TiffinGirls and Tiffinboys