Hello all, little bit of an update!
So after waiting 3 weeks for the new mechatronics to arrive from Europe, the part was fitted, and all seems (fairly) fine.
All faults have gone, the car flicks through the gears much quicker and smoother, and it feels like it has more "get-up-and-go".
However... I'm noticing the car clunks when I come to a stop, going from 2nd to 1st, and then almost seems hesitant to pull away, again clunking and juddering a bit as it goes through 1st and into 2nd.
As this mechatronics is from an audi, I'm not sure if it's an issue with the unit and it not being happy that it isn't a Porsche part. But the mechanic did also mention that the dual mass flywheel is on its way out, and will need replacing in the near future. From what I've heard this isn't an overly expensive part as such, but there's a lot of work to actually get to it, and replace it. He's said that whilst the transmission is out, I might as well look at putting a new clutch in, and gear position sensor.
Car will be going back to the garage and plugged in to see what may be causing it, but I'm interested to know if anyone else has had this issue (regardless of mechatronics being replaced), and what it might be. At this rate, Christmas is cancelled in our household!