A4 3.0 cab power steering dead?

[A4B6Cab]

My A4 cab has been squeaking on and off for awhile, only on full lock at low speed when parking up. Tonight come out of work pulled away and made a really loud, whining noise (not a belt slipping noise, more like a supercharger whine?) so parked up again and got a lift home. Small puddle under the car in work, and noticed a puddle on the drive where the Audi sits. Looks like right hand side of engine bay as you look under the bonnet from the bumper

Any ideas what to check first? Any pointers greatly apprecaited.

Am going back to her in the morning so hoping to diagnose more then
Cheers guys