I don't believe you have to be a perfect parent to HE. At least, if you do, then I am up the proverbial creek... (not that I ever lose my temper or make a misjudgement, you understand )
You sound anxious about your relationship with your son. Either that anxiety is misplaced and you are doing fine, or there are indeed things which you should be improving in that relationship. But either of those isn't actually directly relevant to where you choose to educate him, are they? I mean, if there are things to work on in your relationship, you need to work on them whether he goes to school or not, and if there aren't, then all is groovy, right?
For a child to be angry (= "temper") about something is perfectly normal. Heck, having sandwiches cut into squares rather than triangles can be enough to send some children into total screaming abdabs. The right response to it depends on your philosophy about human interaction and parent/child interaction. If you feel bad about how you respond to your child's anger
temper, then there is a disconnect between what you believe and what you are enacting. That's the thing to work on - integrating your philosophy with your actions.
As for abandonment issues - children grow out of those as they are, consistently and over time, given good reason to believe that they won't be abandoned. If you think your child does have abandonment issues, then it might well be a good idea not to put them in school at the LEA appointed moment, but to wait until they are determined to go - there's a big difference between having independence forced upon you and taking it yourself when you are ready.
Yeah, I really don't think this is about HE, I think that if there's stuff to sort here, you need to sort it wherever you are going to educate him!
"Are my glitches just part and parcel of average parenting - finding ways to deal with the challenges as they come at you, and sometimes getting that (badly) wrong - or does it sound like I don't have enough of a handle on raising my son for us to HE?" Yes, I think you have all the handles you need, though you may need to sit down and think them through enough to boost your confidence that you are a handle-holdin' lady