On the edge of quitting my job today.

Yup - stand your ground. This isn’t your problem to solve (by leaving) it’s THEIR issue to assess properly and agree reasonable adjustments.

You have a job with them.

It’s absolutely up to THEM to give you work to do and to keep you safe.

If they won’t do that (as I think you’ve demonstrated very clearly that they CAN do that via some very easy tweaks) then just sit in the staffroom / offer to help / do whatever you are able.

Don’t willingly lose your job!

If you need to take a sick day to get some perspective / clarity/ calm I would recommend that and then have a conversation with them.

Agree with this, they have a legal responsibility to make reasonable adjustments because of your medical condition. Put it in writing and contact your union for support if you belong to one.

No one should be subjected to this type of behaviour, but sadly I know it happens a lot. Did you outline why you were requesting not going to that class? If you provided medical evidence would this request be classed as reasonable adjustments? Are u able to consult a union? I understand your sadness if you have to walk.out. I would continue looking for another job. If you are able would you consider doing agency work? If you know what particular school you would like to work.at, find out what supply agency they use and sign up. Perhaps you could consider mainstream? I know agency work is only a possibility if you have another source of income in the household. Your health is of vital importance. Don't let people fob you off.

I wouldnt wslk out, especially if you're job hunting.

Tell them they need to put you in another class today and tomorrow and hand your notice in if thats what you want to do.

I’d ask you f they are purposely doing this so that you have to leave? Are they hell bent on reducing the workforce to compound the situation

Ask them for an occupational health referral relating to your condition and the impact work has on it. They late legally obliged to make reasonable adjustment to accommodate your condition. From what you say, you are more than able to perform your role when you have use of a hoist and when working with children below a certain size and weight. This suggest you should be able to stay in your role and go a good job and the school need to make these accommodations.

YANBU at all.
A 'thanks for letting me know' email really wasn't enough (or appropriate) for a message from a staff memeber requesting a change due to health or medical reasons. It should have been addressed properly from a health and safety perspective. They've either skim read or just haven't got the staff and have put you in hoping you won't say anything.
Best of luck today. Hopefully it's a scheduling error.

Go in and have a conversation about it. Its possible the holiday email has been forgetten or not passed to the right person but actually talking through the issues and pointing out that if you work in that class it's likely you'll end up off sick will probably be more fruitful

Don’t just walk out. Go and speak to the Head. Tell them you don’t think they have fully understood your e-mail, as you are still being placed where your health is being challenged.
Insist on a change of class.

Good luck!

Agree, make it their problem. Refuse to work with the class because it isn’t safe. Point out they haven’t carried out a risk assessment for your health condition or made reasonable adjustments.

Sounds horrendous. Your health is always the most important factor.
As an experienced TA I’m sure any school would be glad to employ you and you could find one with a safer environment.