Later Life Diagnosis & Career Change

I have written about my work situation on other posts, so will not go into too much detail here.

Having had a number of health difficulties over the past 3 years with autism being diagnosed late last year, I no find myself out of work since March this year.

I have always worked in IT - something that I have thoroughly enjoyed and been well compensated to afford a comfortable, but not lavish lifestyle.
Now I am at a point in my life where I could potentially have a complete career change, although I really dont know what that could look like.
People say to me that I should do something that I enjoy and all that I have ever known and enjoyed is working in IT (despite it being quite demanding and stressful at times!)
Other things that I enjoy include gardening & photography, but I have no expertise in these things and I dont think that they pay very well.

Whether I look to stay in IT or look for a complete change, I have a number of concerns...

• As an older person (early 50's) I could find myself to be less "marketable" - I remember my father facing this as a challenge 40 years ago
• Being autistic (Asperger's) may put potential employers off. Whilst discrimination is against the law, proving discrimination would be very difficult
• Being autistic + other diagnosed health issues impact my ability to work (eg, I have FND which results in me finding it extremely difficult to get going in the mornings)
• I am used to earning a decent salary above national average, but not massively

Any advice?
Has any other members gone though similar at the same point in their life?