"Very little on risks on all the 'natural options'"
What - the risks of not having pain relief? Are we talking clinical drawbacks?
I've not heard of there being any clinical risks to not using pethidine or epidurals, except in some cases where a mum may be at very high risk of emcs and so may benefit from having an epidural sited early on in labour.
Of course there is the risk that the mother is going to feel more pain without pain relief, but if I was an antenatal teacher I'd feel a bit of a dufus having to explain that.
"Not ONE positive statement about pain relief".
Other, of course, that it is PAIN RELIEF. 
Were you expecting her to give you a big list of clinical benefits for you and your baby to taking pethidine or having an epidural
You'd have to do quite a bit of digging to find any.
"the heavy information on how 'most' women feel desperately ill having the injection at third stage of delivery was fairly annoying."
Did she actually use the word 'most'?
Challenge her. Go on, I dare you. Ask her for the research to back up her view that the majority of women react badly to syntometrine.
" I had to specifically ASK if women who felt ill were provided with anti-nausea meds, and only then did she acknowledge that this was the case"
They are. They don't always work. Especially with pethidine. Most women who have a reaction to third stage drugs have a fairly transitory reaction to the ergometrine element in syntometrine. So we're not talking hours. Having experienced half an hour of severe trembling and nausea following the birth of my youngest, I can vouch that it can spoil things somewhat, and had I not been (like you) at especially risk of bleeding, I definitely would have avoided it.
It's the ergometrine element that causes the problems by the way. Not all hospitals use this.
Anyway, show your DH this: here
Then show it to your antenatal teacher!
"I am far more negatively affected by this kind of judgemental crap than I am by an 'anti BF society'"
Actually if you lived in a society where bf was the norm and you'd grown up surrounded by the sight of babies of all ages feeding at the breast, you probably wouldn't have spent 5 minutes agonising about any of these issues. The fact that it all worries you so much - the appearance of your breasts, how you're going to cope with breastfeeding in public, your worries and expectations about things going wrong, what other people will think about your decisions about how you feed your baby - you probably wouldn't be having any of these thoughts........