Is it possible, via VAG-COM perhaps, to disable the auto lock which locks the doors when driving ?

It irritates me hugely and I've lost count of the number of times I've got out to open the tailgate or go in the back door forgetting to press the unlock button

Yes, it's certainly possible via VAG-COM. Have a flick through the central convenience module options.

It is also possible to program unlocking when the key is remove from the ignition.

ANTI HIJACK

46 – Central convenience

10 - Adaptation

Channel 03 Auto Lock (auto locks car after 10mph)

Channel 04 Auto Unlock (unlock the car when u take the key out)