QRs do say that you can work in your "spare time" or words to that effect, with your CO's permission, as long as it doesn't affect your primary job. They also specifically say that you can work during terminal leave, but not when on a resettlement activity.
If you're on your way out and have lots of leave, then there's no justifiable reason I can see from them stopping you working, but getting to that stage for CS may be the tricky bit. I suspect people who left 10-20 years ago in the pre-JPA era may be disappointed by the "computer says no" attitude we often encounter nowadays.
I appreciate that a while ago, having a well-placed Wg Cdr or Gp Cpt willing to push your case could work wonders; but nowadays it seems you're often told "the system can't do that."