@Applerumbles is your mental health considered a disability? And if so, has this been communicated to your employer? I mean it definitely should be considered a disability if you have been off work now for well over a year with it, as the definition of a disability under the equality act includes mental health issues that lasts for 12 months or more.
I think you are getting a terrible time here, and even the posters who have declared how terrible their own mental health has been and have still done XYZ. It’s not a competition, each persons mental health illness and journey is their own, and the severity of it and how it effects them is completely subjective, so it’s irrelevant how others have coped or pushed through , despite being very seriously ill, you aren’t them and they aren’t you.
You have mentioned you have a union, I’d start by getting in touch with them, so when you do arrange contact with work, you can have someone speaking for you on your behalf if need be, and they can offer you advice, and contact your work on your behalf if need be.
Lots of posters are judging you for not being in touch, but then failing to recognise and include in their comments that your employer has themselves failed to also be in touch throughout your absence. You have said yourself that they haven’t contacted you at all, not that they have and you have refused to engage, so the employer has almost certainly not followed their own absence policy, unless at the beginning of you being off, you agreed a certain level of contact and they were happy to allow it to be nothing. Either way the onus is on them as the employer to be arranging adequate contact that takes into consideration your mental health needs. You don’t say whether work caused your illness ( apologies if you have mentioned this further on I didn’t get to read the entire thread) but either way, depending on the reason, they have to apply a level of contact which is considerate of your mental health and illness.
Some posters have also seemed to miss the fact that whilst you have been off for a significant amount of time, you have also worked there for over 20 years, so you have a longstanding relationship with this company, which speaks volumes and should be taken into consideration when people are being judgmental and saying you need to leave. If you have worked somewhere for such a significant length of time, so long it would likely be the main job in your working life, it might not be as simple as just handing your notice it. It’s a process for you to get through mentally, and you don’t have to rush that.
It’s unusual they haven’t made contact until now, or maintained it throughout, but again, why should you have to be the one responsible for chasing that up? You have stated you have been significantly effected by your mental health, including being admitted into hospital for a while, so I imagine at times even getting up from bed some days felt too difficult, so communication with a workplace isn’t always going to be something that feels possible for you.
Going forward, I’d get in touch with your union, they can advise you on how to respond initially to your employer and where you can go from here, including agreeing a reasonable communication frequency, and who that can be. When it comes to mental health/ disabilities, it might be that frequent contact or any will be detrimental to your recovery, so legally you can nominate somebody to communicate on your behalf.
Id also hide this thread, or just stop engaging with it. A lot of comments have been awful, and lacking any sort of compassion for a person who is quite clearly very unwell and needs support. It doesn’t cost a thing to sometimes cast aside your judgements and try and see it from the point of view of someone else, especially when they are explaining how Ill they have been , and how little quality of life they currently have. Kicking and piling on someone when they are down is just cruel, and it shows those people who truly cannot empathise.
Good luck Op xx