Your first is half a day. Will go over the. Certification process and how to notify and when.
Go over the regs briefly, might ask some questions but nothing too hard.
Will ask go see you insurance and calibration certificate for your MFT.
You need a couple of books and documents. They give you a list on the NICEIC website.
You need a job to show them such as a new circuit or fuse board change. Can be your own house for the first assessment. You will be asked to isolate the board/circuit and demo some testing.
At the end of the day they are not there to catch you out they want you to join unless you are a muppet. As they ultimately want your money!
Only ever heard of one person failing an assessment and that was because his work was awful.