The M7 is just situational judgement, from researching on here it's pretty much as everyone suggests and that you can't really prepare for it. Read the passage and put the 4 answers in order of preference 1st to last.
I honestly didn't practice it as it's down to an individuals characteristics and the answers 'should' be how you would deal with a situation personally. Apparently how you answer can be used in interview as well so best to answer honestly and if/when you are asked at interview stage, it should be a natural answer rather than one you think they want to hear.
I've also read a lot on here that it's not a pass or fail test, just for the TOC to see what kind of individual you are. Take that how you want though, it's obviously there for a reason but go in to it with an open and honest mind and handle each situation how you would in your every day life. Good luck and let us know how you get on.