Current boss doesn't want me but can't start new job for a month

[murree]

I transferred to a new department a while ago and very quickly found I didn't like it and became overwhelmed with the stress of the job and workload. This caused severe anxiety and ended with me being signed off for 2 weeks (This was a week ago so half way through my sick leave).
I have in the last week spoken to my old department and they have a position coming up that I can go back into but it doesn't start for another 4 weeks after my sick note runs out.
Now here's the thing. My current manager is aware I am going back to my old department and has made it very clear she wants me gone asap.
Both myself and my new manager have told her that the role isn't available yet.
What do I do? I understand she doesn't want to pay me out of her budget but I can't help that the new job isn't available yet, if it was I'd go now!
Should I just try and get signed off for the last 4 week's? I don't feel I can go back now as quite frankly she has made me publically feel like a burden.
Can she force me out sooner?

Provided you've been employed there more than 2 years, you're a protected employee and no she can't. I'd get signed off for another 4 weeks if I were you

Yes I've been with the company well over 20 years!
Thanks for your advice x

I wouldn’t get signed off unless absolutely necessary. Why taint your attendance record and (unless you get full sick pay) suffer financially? Make it known you will be back to work on x date then if she doesn’t want you there she is free to put you on fully-paid garden leave.

Do you have a confirmed role to move to ie a written offer letter from the new manager? If so it should have your official start date on it which you can provide your current manager and say you will return to your (current) post on x date, to enable you to hand over your current responsibilities as per your contract of employment.

Sometimes laying the facts on the line to a bullying manager and citing your contract, puts them back in their pram and gives them a reality check you're moving on, head held high and I bet they will suddenly become all pleasant to you as if by magic .

I agree with flowery don't sully your record, you have every right to be there. 20 years is a service history to be proud of.

I have a date to go back to my old department of 15th September.
With regards to tainting my record, as I'm currently signed off, continuing it wouldn't make any difference as it goes on number of cases of sickness not how long they are for. And yes I get full pay thankfully.

Yesterday I got an email from HR as they has rescinded my contract! Turns out my current manager had told them I hadn't even started with them so they cancelled the job offer, thankfully I put that right.

She has also sent an email stating details of why I'm off sick at the moment to me cc'ing in other collegues. Talk about humiliating.
I have been told (not officially) that the only option for them if I come back and they don't want me there when this sick note runs out is to ask me to take 4 weeks unpaid - This I can't afford to do.

I don't have anything to hand over as I was still in the training phase and I hadn't taken on my own workload yet.

I really feel like I need to just stay signed off. I don't want to but I don't want to return to that office even more.

Oh and to top it off even more a family member (Not very close but still) passed away yesterday 😥

And as I'm transferring departments there is technically no contractual obligations, for example no notice period etc

She has also sent an email stating details of why I'm off sick at the moment to me cc'ing in other collegues.

How does HR feel about her providing this sensitive (DPA) or special category (GDPR) data to other employees?

Makes me wonder what this manager's turn over of staff for this role is, and if she is the problem.