Quitting job affecting universal credit

I started working 3 days a week and put my daughter 3 days a week in nursery which I also think is too much for her. I've been at the job for 10 months but I don't like it. It's getting quite a toxic environment and my mental health is deteriorating because of it. I've been signed off for a month by the doctor but I don't want to go back. That instant relief of not having to go in was great but the thought of going back there is beginning to stress me out again. I do get universal credit and they're aware of my mental health condition but I don't want to get sanctioned because I've quit my job. I was thinking of stopping working and potentially getting back into studying instead of part time work. Has anyone been in a similar situation? Would appreciate some advice, TIA x