Kyrbo:
This is exactly what I meant. Long trailer gives you more time to correct mistake without shunt. Of course there are places where short trailer is easier becouse long one is just too long for easy reverse
True comments. At the end of the day tho, drivers can adapt to any trailer and situation, where as the screwdrivers allways struggle! 
JayHoe:
Go on! Be the ‘King of the Road’!It is NOT as difficult as you might think (shhh don’t tell anyone) with the worst part being reversing. I passed my class II about a year ago, and then my class I about 2 months later. The first time you actually drive one, you will be nervous as hell - but when you stop and get out and see the size of the vehicle you drove you will grin like a cheshire cat!
£10 says you will enjoy it!
AHHHHHHHH THE GRIN AND THE SMILE I REMEMBER THAT I WAS WELL CHUFFED
go for it mate and good luck. i think the firm are just protecting their investment in training you. as has been said before, GOAL if you are not sure when reversing, it takes less time than filling an accident form in.