How do I unlock my bootloader with Omnius?

I want to unlock the bootloader of my Carrier Locked O2-UK Xperia Play. When I go into the service menu and check if my bootloader can be unlocked it says "allowed:no". After further research I found out that there are multiple ways of unlocking it; one of them being Omnius. Which one of the licences do I have to buy to do one unlock? Some of them say "No Xperia" and thats why I am confused.