I read your thread indiedog and a new battery was the next thing on the cards. Also thank you for following up on your thread and not leaving it open!
So the two new parts from RockAuto arrived (very quickly US to NZ) and I have installed them today. I cleared the codes on my Bosch OBD2 reader as I didn't have access to the WJ Diag software currently, but ABS codes cleared fine.
I took it for a quick drive and it changed smoothly!! No more ABS light, no more handbrake light, no more engine light, no more transmission limp mode
JeanLuke you were right - the ABS fault was causing the TCM fault causing the ECM fault.
Thank you all for your help!