(senior) finance business partners are the immediate next steps which comes with a good increase in pay (and responsibility). Lateral shifts into other areas also look to have high ceilings, however, I am not 100% sure yet since I've only done one rotation.
I think by buying your time and diligently chipping away at mahi regardless of the role, you will move up the ranks. Promotional opportunities are there as well as employment opportunities as council gives priority to those who have worked there before (as I've been told) they seem flexible too with uni students. By giving them the flexibility to be able to study and further better their opportunities to then either come back to council or move on to other career pathways with their degrees.