I have to agree mate it is a totally different level driving a truck. I never thought it would be easy but when I used to go with Dad he made it look easy but that is what comes with experience. I had three days where things wasnt going right, 1 day it was clutch control, next day got the clutch control okay but was forgetting my blind spots, then I got them both ok and was not judging islands properley and causing other drivers to slow down. Then the next day it all just seamed to come together and 3 days later I passed.
My examiner always used to say you will make mistakes during the training but the last couple of days you should be driving it confidently also it makes a massive difference how you recover from those mistakes.
Good luck mate just take your time and it will all come together nicely.