Right, your profile says your from the UK, so first things first, You can not be sacked for genuine illness, which this most certainly is.
I don't know your full history but if your condition has lasted or is likely to reoccur during period exceeding 12 months, you are legally classed as disabled and will therefor be covered by the Equality Act (EA), it used to be the Disability Discrimination Act but then everything, - racism, sexism, ageism, disability got mushed up together in to one piece of legislation.

What does this mean?? Your employer is LEGALLY OBLIGATED to make reasonable adjustment for you to enable you to continue working, it may be something formal and contractual such as an alteration in start/finish time or shorter or fewer days either for a short while or an extended period of time to be periodically reviewed with input from yourself and OH

For me all i needed was to informally tell my boss that I just need to be left to get on with things, and I will look after the rest.

to be clear you can NOT be fired for getting ill, there are laws that protect you.
Most doctors will agree that working is good for you (as long as you truly are capable) and it really does sound like you want to be working, and you have excellent support from your line manager which is important.

I suspect this upcoming meeting is about working out the best way to get you back to work as successfully as possible and for everybody to be clear on what their role is in supporting you.