These are some push-button codes for the PAL version of Guitar hero:
Yellow, Yellow, Orange, Blue, Yellow: Your character will play Air Guitar, in other words have no guitar.
Blue, Yellow, Blue, Orange, Blue: Your character plays the Guitar Hero Guitar, or a guitar that looks like your SG control.
Yellow, blue, blue, orange, orange, blue, yellow: This is a crowd cheat, I'll let you figure out what it does for yourself.
Yellow, blue, yellow, yellow, blue, blue, orange, orange: Another crowd cheat. I'll let you find out this pushbutton code on your own.
Orange, blue, yellow, yellow, blue, blue, orange, yellow: Your guitar meter will stay on green during quick play. I'm not sure if it'll work during career though.
Orange, yellow, orange, blue, blue, yellow: No Venue, which means your background will be blank.
Yellow, Orange, Orange, Yellow, Blue, Blue, Yellow:You will unlock everything, including, all songs, all characters, all guitars, all guitar skins, and all videos.
I believe that covers all of the PAL Guitar Hero cheats.NOTE: YOU CAN ONLY ACTIVATE THESE CODES WITH THE GUITAR HERO SG CONTROL. YOU MAY NOT SAVE ONCE THESE CODES ARE ACTIVATED.