1- Don't be so flipping daft. Many of us went into the job with no knowledge of the blue book (pre-internet days) and we got through OK.
2 - Don't be so flipping daft. VATSIM is to Air Traffic as Grand Theft Auto is to driving lessons. It's nowt more than a game. I'll say no more before I get attacked by the massed ranks of the VATgamers.
Most common reason for failure is not putting enough effort in. Work hard and you should be OK. Don't fanny around, it's only a few months out of your life before going on to an operational unit.
That said, good luck with it all, despite the moaning oft seen here, the majority of us actually enjoy the job.