I thought I'd share my experience. I applied to the Generation EasyJet programme last year about July, I only sat my technical day in March (long story).
If you are going to CTC I would say SkyTest is the closest you will get to the actual tests you will experience that day. I couldn't get the audio to work with SkyTest through my PC but they very kindly issued me a license for iPad. I wouldn't recommend using the iPad for anything requiring the joystick as the on-screen control is not helpful. I would use the auto-trainer function as it pushes you to the limits but you will find on the day when you sit the test that it's pushed you further than you need.
The maths test is multiple choice and I highly recommend using latestpilotjobs.com, merely for practicing quick calculations. You only get 1 A5 (half of A4) sheet of paper and I had several square route and currency conversion questions which I had to answer using educated guesses. I passed this section of the test (I didn't ask for my score).