I just did my Stage 2 and so I can give those in need some feedback as well.
The maths are quite easy, you have 30min and 20 questions, becoming progressively more difficult and I suggest to start with the difficult ones because they take longer to solve, not because they are too difficult but because without a calculator you have to do all the maths step by step, and they are worth way more, also the easy and medium ones are really basic. The questions are 95% about time and distance and 2 or 3 about bearings and trigonometry.
The last math problem I remember to be like this: A plane flies 1970 miles from point A to point B, at an average speed of 460mph. The fuel rate is 30 lbs/min. In Kg how much fuel is used during the flight?
The physics are even easier I think, I finished in less than 20min. Practice Newton's equations of motion, levers and weight distribution, basic circuitry, adding resistors in parallel, springs in parallel too, Boyle's law for the last one (most difficult). They involve straight forward calculations, no need to deduct or anything.
The last one as I remember is: A volume of gas starts at a pressure of 30atm and a temperature of 59ºC. If the pressure is increased by 2atm and the volume of the gas remains constant, what is the new temperature? Remember that in this formula you have to use the temperature in kelvin and then in the end convert it to Celsius.
The cognitive part is composed of 38 exercises and it's exactly like it says in the document they send you to prepare for the test. It's easy, don't have to practice much but if you want, I bought the Skytest software and it was very close to what it came out in the exam.
The Red Dot test is a bit tricky and I didn't practice this one but you have a couple seconds before the test to try it out and get used to the joystick. You pull towards you for the ball to go up and push forward for it to go down. You have to twist it right and left for it to go sideways. You have to keep the ball centred for 4 min, you need to focus a bit one this one.
The FAST exercise was more challenging than I expected because I was practicing the one on Skytest which is not complete, it doesn't test all the aspects like in the test. You will be instructed before it starts you will have 2 attempts for this one. You have to manage a lot of things in a short period of time and it's quite hard to do it all so you have to divide you attention. You have to fly the crash course, answer questions (even though basic they are a lot and come at the same time as the ATC is telling you stuff), you have to remember what the cockpit looks like, how many different voices did you hear, how many beeps, how many planes you saw, info about the waypoints, etc.
Finally, the Fixed Wing is the one I think I failed, wasn't so difficult but I cut corners by distraction. You are given a certain route to fly with specific values for speed, altitude and heading and you have to go through all the waypoints.
You can take as many breaks as you want between tests and as long as you want them to be so that's cool, helps you relax.
Hope this can be useful.