I done mine a few months ago with gtr.
On the assessment day i done all the assessments then pre filled the 6 answers for the mmi interview and then at the end of all assessments done the sjt.
You don't find out on the day if you pass. It took approximately 2 weeks to get the result
I actually found the assessments relatively easy, don't over think. The worst i found was the 2 hand co ordination which i thought I had failed as I am no gamer and kept going off the track but kept calm and carried on. The joy sticks ping back so I found it easier to hold them lower down with the edge of my hand resting on the desk for more control.
Good luck!
Just to ask, did you apply to Southern or Southeastern?
