my understanding is that the EP instructors will be asking 5 questions. you will need to get 4/5 correct if you get less than 80 % then like EP's you will be asked subsequent question/s to get 80%. A fail will mean removal from the flight and an EP total resit and exam.
Apparently been operating in London for some time and no one has failed up there. Not designed to "catch" people out but to comply with latest missive from CASA.
EP instructors will use the same level of common sense that they always have and it will be done fairly i am advised.
As far as when you do the test....
Will be apparently only one (1) person per crew that will be requested to participate. And will only be done something like 2 days per week. Not sure what days or whether they will be the same days or random like D&A tests.
Crew can do it prior to sign on in a room allocated for the purpose and when you do the electronic sign on you will be notified by Pop up screen whether you are required to attend.
If you do it after the briefing you should notify the CSM that you are going so the bus can be held for you. No penalty for doing it before or after briefing....
That's all i know at this stage