Hi mate,
I didnt use vetassess but I did it last year with another company as metal fab.
To be honest all the questions asked are "bread and butter questions" what tools you use for this process, that process. How you work out the circumference of a circle, how you work out angles- don't overthink it!! How to set up machinery etc. Just be honest with them.
The assessors are tradesmen and are friendly- don't expect a bloke in a suit, more likely in work clobber, chances are he/she has just finished work. They won't sit there with a clipboard grilling you about argon gas- they don' want to know how it's made, just how to use it.
Hope this helps, good luck