Hmm. Thinking about it, you just reminded me, Jennie...
Both Neil and my sister administered my immune system booster jabs at home last year after each chemo with no training whatsoever (no medical staff or community nurses available to show us how to do the first one either - or subsequently - so we were definitely self-taught!!!).
All the instructions were included with the individually sealed needles/serum.
Only reason I didn't inject myself is that I'm a proper wimp with injections!!!
I think I managed to pluck up the courage to do the very last one on my own.
So, if Jennie, me, and members of my family can do it, plus the (millions?) of Type one diabetes sufferers etc., it can't be that complicated, surely?