Sounds like you got a good chance, I dont know why they dont turn up if they have a chance lol, ohh well should work in your favour.
Well if you get on with the guys in the w/shop and show interest when they give you a task or little job, this is a good thing as they like to see team work, plus after you finish your three days the manager will ask the other tech's ( who you've been working with) how you got on and get them to wright abit about you and what skills etc you have.
Hope this helps lol.