Welcome to this forum, Tired Mum. No partying here, alas - it's more like "the morning after the night before"!
Not much to add to Guest55's helpful comments. You're already going through the Q&As, and you have the headteacher's full support.
If the head means what she says, she can help by making your daughter stand out from the crowd (academically speaking). Can she predict high level 5s, rather than just 5s? Will she use words like "I very
strongly support ........ considerable
academic potential ...........an exceptional
Go for as many appeals as the system and your stamina permit!