hey clairey fairy!
To be honest you can't really cheat the personality questionnaire! I failed it the first time round and just passed it the second time I took it. All I can suggest doing to help you is to look into the job properly, read through the nats site and get into the mindset of exactly what they are looking for. Thats the way I did it, got myself into the mindset of being an ATC and exactly what they need.
Even if you do cheat the system, the quick fire questions at stage 2 will catch you out so theres really no point on doing it!