I wore a suit and would recommend you doing so too, shirt tie and trousers at the very least.
I didn't have a card either, just knew my number off by heart so as long as you have the number that should suffice.
Thanks Rickmcc78, you've been a great help. I much prefer a suit if I'm honest, did you include a waist jacket if you don't mind me asking ?
When was your assessment btw? I'm guessing you was successful