Well, a huge thanks for recommending Bristol Gearbox Centre.
I dropped in for a chat and after a test drive and full explanation of the gearbox workings and the cause of my fault they offered to do the work there and then!
£700+Vat for the Mech Unit Valve body replacement inc fitting. Done and dusted in a couple of hours while waiting in their nice comfy waiting room, I just had to wait a half hour for a vehicle lift to come free. They then took me on the calibration/test drive and made sure I was happy. Not sure what software they used but it wasn't VAG COM, it moved on at each step once it was happy the driver had done the right amount of time in the right gear.
Have to say, it's a different car. Pulling away in 1st or reverse is silky smooth either creeping off throttle or light throttle or on a bit of power. Gearchanges, although good before, seem smoother too. Very happy bunny here!
The diagnosis was spot on and very different from the try it and see approach of another place I tried (would have wasted £1k on clutch pack change if I'd taken it there).
They have a nice setup with a clean workshop, 4 vehicle lifts and a lab/workshop where the repair ECU's and refurb the valve bodies.
There were another pair in the waiting room with their Audi A4 which was done while I was there, a broken link in their ECU was the cause and this was solder repaired under microscope rather than replacing the ECU. They showed the owner the fault and let him watch as they fixed it. Great service.
Can't recommend them highly enough, and they really are experts in DSG, S-Tronic and Multitronic.
One very happy bunny here :) Sounds like a lot of money but it's really been the only spend it's needed outside of routine maintenance in the 3 years I've had it. They also put my mind at rest about my recent VW DSG oil change, the oil that came out when they dropped it to remove the unit was lovely and fresh.
