Mr Blue 92:
Today is my first day on pprune too. I am going for my stage 1 on April 8th and your preparation sounds exactly the same as what i'm doing. Once you've learned. all the info in the 25page document it will stick in your brain, trust me! You just need to keep refreshing what you've learned and make sure you look at it every day. I am currently doing the cubes, diagramming and S/D/T calculations and also purchased the feasttest preparation tool.
FEAST Test Preparation Tool - Feasttest.com It was around 25euros but I've found it really helpful.
This is also a link I have found useful for S/D/T
Speed Distance Time | OASC: RAF Officer and Aircrew Selection Centre
Hope this helps and good luck in June!