Compatible Steering Wheel Lock? (UK)

Hello,
First-time buyer here. Ive just bought my first car, a 2005 Prius (picked it up on Friday). I can't work which exact model i have, which i need in order to find a suitable steering wheel lock for it. On the keeper slip it says Prius T4 VVT-I AUTO. I bought a Stoplock Pro from Halfords, but it didnt fit so i returned it (and the workers in the shop couldnt advise on which one to get). Does anyone know which one would fit my model?
Any help would be really appreciated!