Headlight set/plug wiring schedule etc

Does anyone have any wiring details for a 2015 a6 c7, specifically for the headlights and how to release the plug! 
I’m trying to retrofit LED fog lamps (my car has ACC, so no fogs). I was planning on tapping off the ‘all weather’ lamp wiring (& hoping the control unit can be recoded to come on with sidelights) but:

1. I can’t get the plug off the headlamp unit!

2. When I opened the all weather lamp cover on the back of the headlamp to see the wiring colour, turns out Audi use black wiring throughout the internals, so I can’t identify which core in the plug on the outside is which.

plan B is to add 2 new cores through the plug to tap into the wiring inside the headlamp but that’s really, really tight! So if anyones got wiring data for the headlamps showing which core does what I’d be really grateful

I can both see & reach (just) the plug but can’t figure out how to release it. There’s a catch on the side, I’ve tried moving the catch in all 4 directions (up, Down in & out) but no luck in releasing it!

also open to any other ideas to get this done?

cheers all

Dave F