No, the training does not cover conjoined twins or other rare conditions but of course it includes breast anatomy and some special needs - but to be honest, a vast amount of technical knowledge is not as important as the skills needed to make a group work well, and a deep understanding of what most women need to know in order to bf with confidence.
If you read the link I posted it will tell you more, including details of Level 5 and Level 6 courses which would allow you to become a breastfeeding counsellor who is trained to work with groups as well as individuals.
It worries me you are claiming you will be 'training with Jack Newman' - you are planning to follow some e-learning modules which he has devised. They will be good, because he is a respected name, but they are not (AFAIK) interactive and he will not be your personal tutor.
I'm not really advertising the NCT - there are other routes to being a credible breastfeeding supporter who can work with groups, and NCT is the one I know about, that's all. I do care about the quality of antenatal breastfeeding education and support on offer to groups of women, and I do think anyone offering this, especially for money, needs to be trained and supervised. Just knowing a ton about breastfeeding isn't enough.
I have sat through (free) workshops and classes myself, where the person running it was perfectly nice, plus informed and knowledgable, but the educational and support experience for the parents was boring and unhelpful.