These 2 apps should help give a sense of where you can work on different causes in the Civil Service:
https://highimpact.shinyapps.io/impact_areas/
https://highimpact.shinyapps.io/civil_service_jobs_explorer/
That said, for non-civil servants—I would strongly suggest focussing the first role you get on skill development and understanding how government works, rather than trying to go straight into the most impactful area.
Civil servants are expected to move around a lot, so you can find the most impactul areas once you are in, and demonstrating good generalist skills is one the key things that will make moving around easy.
This article is really useful- thanks for writing it Kirsten.
Couple of opinions I’d add:
If you don’t get on the fast stream, do apply for other jobs. The fast stream seems good, but I’m not convinced it’s much better than just getting a job in the Civil Service and just moving around independently.
Applying for jobs in the Civil Service is a specific skill that you can get better at. Apply for a bunch of jobs, get feedback, and try and improve your scores.