rickandmorts I'm so sorry you're miserable at work and feeling unable to do your degree. Have you done any studying at this sort of level before? Could your reaction to the studying be to do with needing more support academically or do you think it's more about it tying you into this career you've decided you hate - and that very idea just has you paralyzed with horror?
On the falling out of love with your chosen career path I think there are various possibilities. You started really young and it's easy to make the wrong choice at that sort of age (it's easy at any age really, but even easier when you're young), but it's also possible for a bad experience to spur you to something and then, when you get some space from that experience, you can fall back in love with all the things you originally liked about it. There's also the possibility that your approach to work predisposes you to eventually hating it. This has been my experience. I appreciate you aren't me and I'm not assuming this is how things are for you, but it took me 30 years to work this out, so I'm going to put this here in case it is like this for you and you can gain something from my experience.
I've gone through several "careers". I tend to be pretty good at my jobs, I pick things up quickly, get promoted, etc. but after 4ish years I start to be really dissatisfied with how I'm being supported. I find my managers seem to overlook important issues, let things go that other staff do, make decisions that make my life much harder. Expect me to get on with it. And I resent it. There's normally at least one spectacularly bad decision by upper management that's totally deaf to the work we're doing on the ground and I begin to think the entire senior management don't care, don't know what they're doing etc. I get disillusioned, stop performing as well as I might, stall in my trajectory. Then I move on to another job. Sometimes just a little different, sometimes just a bit different. And I shine in my new role and feel justified in my assessment of my previous workplace. And then the patter repeats. It took dropping out of work for a few years to be a SAHM and finding the pattern repeated there - when I was the total boss! - to realize it was about me and my expectations. When I start I'm learning which is fun. I gain skills which get recognized and rewarded which is a bit of an ego boost. The the expectations start getting higher and I'm put on the spot more. I gain more skills but it's very incremental and not as satisfying. I'm expected to be able to cope. The terrible management decisions have actually always been there (because managing is, in fact, pretty hard) but I didn't notice them as much when I was more junior and anyway I had exciting things to think about. When I'm more experienced it's my job to smooth the edges of bad decisions so we can make the best of them but rather than seeing that as skill I'm building I saw it as me covering for incompetent management. They weren't actually incompetent, it's impossible to get everything right all the time and to balance all the competing needs fairly. But I wasn't really seeing that at the time. Instead of understanding my job as making things work for the company as a whole I thought of the company as being there to make my job as perfect as possible. (In the NHS you may have a more legitimate case for expecting the organization to be focused on making patient outcomes good, but there are probably still a lot of pressures that mean they have to compromise quite a lot.). I've realized since that I was probably a bit of a nightmare employee some of the time. And I really needed to view my role differently - as more about lifting the company up rather than just doing my job well and expecting perfection from all my managers. I also realized that a fear of failure often had me pulling back just as things got really hard.
I haven't gone back into the workforce yet, so I'm not sure if I've found the solution to my dilemma. But I'm hoping framing a job differently will help me avoid that 5 year itch and be a better employee and manager.
I wasn't bullied at work, but it sounds like the lack of support you had is a big factor in how you view your career now. If your situation might be anything like mine, understanding that your management are always likely to be a lacking wherever you are (hopefully not that bad in the future) may help in thinking rationally about your options and disentangling your dissatisfaction with your workplace from your dissatisfaction with your chosen career path.
Do you have the option of postponing the degree while you sort out you ambivalence with the job? Could you move to the same role in another area to see if a new start away from the bully helps?
You are still really young, so changing career now will be relatively easy. You'd still need to find another career though, and deal with disappointment and difficulties there.