Wiggly, I would be annoyed because I don't think that the workplace (in general) is for children.
If risk assessments have to be done for employees, then re-done for pregnancy, then surely it would be an absolute necessity for a risk assessment to be put in place for children in the workplace? Why should an employer legislate for children in a working environment?
There are obviously some working environments or courses where it would not be a problem - the examples of after school club and breastfeeding support training would be entirely suitable for a baby obviously.
I do however think that a safeguarding course requires 100% concentration from all people on the course - OP as well as the other course members.
Whynow of course you should ask the course provider first of all, if you don't ask you don't get.
If they say no, then ask your husband - he may say yes (from what you've said probably not, but you have to ask to allow him the opportunity to step up and support you) - explain to him in straightforward terms why you want to work, and why it's important to you.
If he says no, then ask your friend - you said already that she would more than likely help, so you at least have that option.
Good luck with everything, I do think you need to address the lack of support from your husband - really be honest with him about what you want and why and hopefully things can get better on that front.
I don't think people were being mean fwiw, just some honest opinions - will probably make for easier reading in a day or two when you're not feeling so defensive (I mean that in a nice way).
Hope you manage to get the course done, and start your job with minimum troubles. 