Gone for the sensors in the end. Spoke to my dad and he had a camera on his XF, said that you end up watching the screen rather than using the wing mirrors. Could fit the camera later if I decide to.
The daft thing is my car only gets parked in three places. 1. Work, in the same spot. 2 Home, in the garage. 3. In the furthest corner of the supermarket car park.
Thanks guys.