For the Quality of Written Communication (or A03) questions, you must state exactly how you get your answer, going through every single step in detail. For example, if you're finding, say 97% of 600, you don't just say '97% of 600', but '600*0.97' for FULL MARKS.
To be honest though, this is the first paper so it will be one of the following for us:
1. RIDICULOUSLY LOW grade boundaries with harder style questions
2. Normal grade boundaries with easier style questions
The Sample Assessment paper is ideal for trying, but there is also another mock paper on the Edexcel website for 1MA0H. You need to phone publications: 01623 467 467 who will then send you a copy of the password protected new mock paper.
Hope this helps.. x