Incase anyone cares, I used a vernier to swap mine and tracking remained correct
Mark the nut and the rack end threads with tippex so you can ensure they can be returned to where they were, using a 21mm spanner crack the big nut from the track rod end, on both of mine the nut was seized on the rack end anyway, but if you tippex it and it moves you can put it back where it was...
Unscrew the rack end from the track rod end, of the nut is free keep it somewhere near (use a 13mm spanner on the hex section)
Once free, ensure your tippex marks are aligned and using a vernier set it to the correct distance from end of the rack end to the nut
I then swapped the rack end and wound the nut on until it was the same distance from the end once more, now mark it with tippex and ensuring marks stay lined up as these will move easily being new, tightened it up so the marks were aligned, this may take a few attempts
Ideally do one side at once and test drive, then adjust so steering wheel is straight if it’s off, then do the other side and repeat
I actually did both sides of mine at the same time in this manner and it was cock on first time and bang on (the vernier worked a treat)