Ok I once opened a van bonnet like this, might be worth a try!
I used a long slim bar with a small hook on the end with the car up on ramps and i pulled the catch that the cable would normally pull. Not sure if it will work with a golf though. Just something to consider.
The other way is to from underneath, completely unscrew the catch from the bonnet (if its a screw type!), getting access will be hard though.
