In the theory test? I didn't find any real hard bits when I did mine in January but I did have a problem remembering the road signs. But if you're using the practice disks you'll be aware of the area's you need to practice more.
Don't loose sleep over it though as the test is multi choice and some of the questions on the practice disk are in the test (like the road signs
)
For the second part, the hazard perception, just keep your eyes peeled and start your clicks as soon as you see the hazard, you'll get a good feel of this from your disks
There's an on line practice test here if you fancy a change from the disk
Free on line DVLA Theory test