Thanks for the reply!
I've read so much about the judder/shuddering being down to the speed sensor failure and a transmission oil change. Once done, and with some XADO added, seems to fix these issues.
To me, it makes logical sense as in full auto mode there is nothing telling the transmission what speed it's going, which would determine when to change gear etc.
In manual mode, I'm basically bypassing the sensors job and I'm gear changing on my own.
Surely it the gearbox or transmission is broke, it is broke, regardless of which mode I'm in. After all it's the same gearbox regardless of mode.
With the Speedo not working, and the diagnostic check only showing a speed sensor fault, I'm hoping my logic is correct!!