One of the big changes when AFCS replaced the WPS was the ability to apply to the scheme and receive an award while still serving.
While this is significant, it's actually really difficult to find any guidance, or examples of how this works in practice.
I therefore can't really add anything substantive here. Essentially you fill in the claim form and Veterans UK do their thing.
I imagine applying to the scheme while serving would be a very different proposition than applying after service. While the intention in the change might seem to be positive, and allow serving personnel to access the AFCS, I would not be surprised if in fact it led to people being out of time to claim.
There may be stigma at being seen as an ambulance chaser, seeking compensation from the MoD. "Bloggs, you wanker, they can't fix the bloody vibrating Ajax 'cos you had to sue for your broken ankle, just because you can't ride a tackle."
Would you make a claim for a mental injury if you still wanted a military career? I was diagnosed with an adjustment reaction in 2008, which I could have claimed for if I'd known AFCS existed. Would I have? Probably not, as it'd be like popping smoke on your medical file, asking never to be allowed near an aircraft again.
It is probably therefore beholden on commanders and medical staff to have an awareness of the scheme and its workings, so that it can be de-stigmatised. It's another reason to do away with time limits as well.
If you are medically discharged from the military, paragraph 5.3 of the JSP says that "when an individual is medically discharged, and has been considered eligible for an ill-health pension, DBS Veterans UK will automatically consider the principal medical condition leading to medical discharge to determine whether it is caused by service and therefore warrants an AFCS award." I'm afraid I don't know what happens with your pension when you're medically discharged, but I think you're entitled to some sort of ill-health pension. I don't know how much that would be. When I was diagnosed with PTSD in 2018 I wondered why I hadn't been medically discharged, and that led me to find the AFCS in a Google search for 'military invalid pension uk.'
When I applied for an ill-health pension under AFPS 75 having not been medically discharged, I was essentially told you have to be completely unable to work to be eligible.