Hi aus111c! Well done on passing the spec testing, I have heard a lot of people saying it's one of the hardest things during the recruitment process. As to your question about the essay: I had to write an essay first thing on my assessment day and the questions asked were 'why do you want to be a pilot, list some leadership positions held, what are your strenghts and weaknesses'. The questions are pretty much straight forward but what I found tricky was to write it all down during the timeframe given (if I remember correctly it was about 10 mins).
So just make sure you focus on your key points and keep it relevant!
Hope this helps and good luck for the 3rd of August!!!
Cheers
Laroux