I would say to use the official DSA book or CD, they have the exact questions that will come up on your theory test. Other third party apps and books are pretty much the same but are just worded differently so it may be difficult for some. And as for the hazard perception test, you are basically looking out for either vehicles or/and pedestrians doing something that may/or about to cause a hazard. For example if you see a pedestrian running across the road without looking, then that is a hazard. Or if a vehicle turns without indication or overtaking unsafely then that is a hazard. There are mobile apps that can help to practice before the actual test. So good luck!