Thanks for the replies guys.
The bit in the manual says this...."Releasing (the parking brake) With the ignition switched on. Manual gearbox - press the switch with the brake or clutch pressed. Parking brake is released".
From what I can see in the UK 2013 spec's, 'hill start assist' does not exist. The auto hold feature only applies to the auto gearbox models.
Looks like I'll have to nip out with a couple of chocks everytime I need to have a steep hill start!