If the FEAST tests NATS are using at Stage 2 are exactly the same tests Eurocontrol use, then if I recall, it's divided into two parts.
The first part comprises of a series of tests to assess your spatial awareness, basic arithmetic and vectoring skills. I think coordinates are involved too.
Candidates get invited to part two upon satisfactorily completing part one.
Part two is slightly different in the sense that a large part of it forms a learning process.
It takes the form of a flight strip display system, which needs to be managed successfully by the candidate for a certain amount of time.
However, before this takes place, you spend a fair amount of time going through some intense learning so that you become competent in the system before using it.
Various announcements are made (via headphones) during the actual test which require a reaction on the part of the candidate. This could involve changing the altitude of various flight display strips, altering the order, modifying ETA's etc...
It's aimed to test how well you can learn from theoretical instructions and then apply them practically. I think it will also test your reaction times and combine that with your overall accuracy.
It's a tough process, but not impossible. As mentioned previously, there's not much you can do to prepare. Getting a good night's sleep is imperative as you need to have a clear head on the day.
ILS RWY27L