Can you drive a restricted 125cc in Scotland when you are 16?

Hey there ...

I'm stuck, I was sure that you could drive a 125cc in Scotland of you had taken your CBT and had L plates on the bike, no passengers and not allowed on motorways. Then somebody told me that you could have a 125cc but have it restricted to a 50cc until you turn 17. Then I got told that I could only get a 50cc and now I'm really disappointed as I just got an aprillia RS125 and I don't know if I can drive it on the road or not. I need help? Anyone? (Good detailed answers please)

Thanks.