alright mate, don't worry to much about the interview, u basically just talk about your experience in your trade! Then 40 set questions he asks you, they will ask you about tig, mig, stick and flux core, they ask questions like ( how do set a mig set up, was gas you use for tig welding and what different kinds of welding electrodes can you get for stick welding ). They ask you what tools you have been using, talks a bit on safety aswel, ( pre starts, and site safety )
as as for maths questions I remember there being 1 question and it was simple, a drawing comes on the screen with a couple of measurements ( basic ie 500 + 250 + 250 = )
I done my vettasses in December 2013, got the results back in 10 days after the interview as heavy metal fabricator.
you will be fine mate, I no 6 or 7 lads who have done it in the last year and everyone has passed.