Are the Cognitive tests hard? also I am not very good at maths, what is the numeracy test like? Thankyou

The cognitive test isn't too hard it depends on the person as to how hard it is seen to be, there are practice ones available that your career centre will give you guidance on how to find it.
The numeracy test has questions similar to your GCSEs BBC Bitesize is a good tool to use to practice getting back into maths, if your not going for a technical trade that requires it you don't have to do it, but it does open up more trades to you if you've done it and reached the required standard for those trades.