Please read https://kali.training/chapter-8/introduction-to-apt/ to get familiar with APT and the way Kali mirrors work.

Then you need to make sure that you have run "apt update" successfully. If after that, you are still getting errors while trying to download files or if the "apt update" command itself is failing, then re-open this ticket and indicate which mirror you have been redirected to (you can see it in the output of "apt update") so that we can double check the status of that specific mirror.

Ran apt-get update again, still having issue.
Mirror is ct.mirror.garr.it/kali
My location if relevant is Eastern Australia

Thanks, confirmed. That mirror is badly broken:
http://ct.mirror.garr.it/mirrors/kali/dists/kali-rolling/main/binary-amd64/ => files dating back to September 1st
But the trace file that we are monitoring has a recent date:
http://ct.mirror.garr.it/mirrors/kali/project/trace/repo.kali.org

I disabled the mirror for now and I'll check with the mirror maintainer.

BTW an italian mirror for an australian user is a bit under-optimized, it would be nice to have a mirror in Australia...

ct.mirror.garr.it should be fixed now, I re-enabled it.