I finally got round to doing mine over the weekend. All good but now need to recalibrate the air path / throttle body as codes P0403-71 and P0405-77 have come back.
I have the MaxiAP200 diagnostic tool which has the service function 'throttle' which says it initialises the throttle actuators for ECU learning values, but no mention of EGR replacement. Just wandering if this function is the correct one and can anyone confirm if they had success using it post EGR replacement?

Just took a step into the unknown thinking what could possibly go wrong!!
The 'throttle' service function on the AP200 does indeed include EGR reset but isn't apparent in the description before launching the process. It reinitialies the throttle body, turbo and then EGR in consecutive steps with ignition on but engine not running.
What a difference it has made, smoother more responsive pick up through entire rev range in all gears.
Thanks again to Jules and all who contributed. It was a tw@t of a job to be honest and took me around 8 hours having never removed secondary bulkhead before.
Now onto investigating the metalic chinking noise from all four corners when going over bumpy terrain..!

Im delighted that you found my link helpful.

As to the noise - droplinks maybe ?? Jules