@careerchange2022 If accountancy is an option you're seriously considering, it's not one with an age limit. To be honest, you're better off entering it as a young'un (with no real commitments) or as an older person (because the kids are old enough to take care of themselves), so sometimes being older can actually be in your favour. The people in the middle who are trying to juggle working full-time, studying full-time and caring for others are the ones who have it the worst.
Re the comments on maths - if you have a decent grasp of maths (can you do the grocery shopping with a rough idea of what you're spending, can you split a bill in a restaurant?) and English (can you read and write coherently?) then you have the level required. It's really not as maths-focussed/geeky as some people think it needs to be.
However, with all that said, I'm not sure it's a career you would be considering if not for the earning potential, and that's not a great reason to get into it.
'Before it's too late' sounds a lot like you're putting unnecessary pressure on yourself, which is only going to make your anxiety worse and trap you in a vicious cycle. I think you need to work at finding better coping strategies, because that would change your requirements and open up many more options, some of which might appeal to you more strongly. You say you've only just started on new meds and with CBT - I think you should give yourself some time to see how those go.
I would also treat the therapy as step one in achieving a better career, rather than step zero. It's a big investment in yourself, it's something you should be proud of yourself for trying, and it sounds like you need to nail step one before moving onto step two, which is defining what your job requirements are. If you skip step one, you're limited step two far too severely.
You're not too old to retrain. You also still won't be too old to retrain after you've spent more time in therapy.