Okay... so luckily I noticed this before I started pulling my headlight units apart again.
I suspect that the problem with my LEDs was not caused by my work to switch from LHD to RHD, but was in fact a purchasing error.
On inspection of the pin layout on the LED ballast, I noticed that it is wildly different to the pins layout of the connector coming from the headlight unit!
Unbeknownst to me, the part numbers for the LED ballasts are identical for many cars in the VW group apart from the last letter.
When purchasing, I assumed that the important part of the number was '4G0907697' and the the 'H' at the end was nothing more than a revision of the same part. How wrong I was!!!!
In reality, the pin layout of 4G0907697H is completely different to the layout on 4G0907697G.
A quick google imaged search, reveals that the pin layout of LED ballast 4G0907697G is identical to the pin layout of the connector from my the headlights.
I have now ordered 2 x 4G0907697G and will hopefully be posting pictures of my fully functional LEDs shortly!