Hi,
squiggle!
The Hazard Perception is a pain in the arse, basically. It was just a fluke that I passed. My sister kept failing on this part and then I found this website for her:
http://www.theory-test.co.uk/asp/hazard_percep tion_info.asp
She did have to pay a little bit for it (I don't remember how much exactly), but it meant she could practice as many times as she needed to on loads of the different potential scenes they might give you. I'm sure it tells you when to click, also.
She passed straight away on her next go! I hope this helps you a bit. Good luck :o) x