Well it appears i may have spoken too soon - sort of.
Had the battery warning come back up so after doing a bit of digging, it appears you need to reset the BMS and one way can be done on the battery itself.
https://www.youtube.com/watch?v=ul8QOfdn_94
I haven't actually been out in the car yet, but i did this reset, left ignition on with radio playing for around 10 mins (engine off), and that seems to have cleared it.
So, i'll see what happens over the next few days
