You'll be given a chart and the usual answer and question paper.
You'll also be given a plog that you'll have to fill in.
The first question will be something like :
1. Your flight will be from N513505.05W to.. blah blah, with a diversion of
N563505.05W (just made up)
You fill in the plog from each way point, doing your drift and working out True etc..
Then you'll be asked question on your route.. E.g. What is the distance from a to b. Or, what is the true heading of a to b. What is your fuel burn for this.. etc Since you're given a chart it's not hard to get things wrong.. it might say what does this symbol mean? Just look at the chart.. Or what is at this latitude and longitude.. and then tick the right answer. You'll also have an AIP that you will need to be able to understand.. it might ask, what time is this airfield open till..
The will also be some other questions at the end about navigation, not to do with any routes.
Work through a PPL confuser, the test is pretty much exactly the same as that.
Oh... I will add, you have to be EXTREMELY accurate. Down to half a degree.. But once you've filled in the plog your pretty much just ticking down answers that you've already wrote down.
Thats pretty much it, alot of people say Nav is one of the hardest but it's actually really easy because hey, you're pretty much planning routes every day when your on the nav part of your PPL, for that reason it makes sence to do NAV as your last exam.