How do you get financial support if you have an undiagnosed disorder?

I know I can't go back to work anywhere until I'm diagnosed, but my doctor said it could take months. The last time I saw my doctor, he said he can't sign me off sick for that long as that would simply be impractical. I don't think he understands the anxiety of this. I've being living in this bubble where I try to be normal and avoid social interations. I didn't think it mattered that I had a disorder if I just kept myself to myself (no harm done = no disorder). It's been going on for 30 years. I've been living in a bubble where I block out any negative remarks from others. I know I'm weird and I've been told that there is something wrong with my thought process and that I'm strange whenever I try to make friends with work colleages. 

I emailed work and told them I was going to ask my GP if there was an alternative way I could get financial support as I don't want to tax my company with months of sick pay. They replied and said I have 10 weeks full pay and 10 weeks at half pay. Should I just show my GP the email? They attached the policy for employees going through hard times. He said that he wanted to refer me to Occupational Health, but it can only be via a phone call and strictly not on the work premises. 

Yikes! I've only recently stopped blocking the reality of my condition. I don't know if it's ADHD, autism, brain damge from a childhood attack or what? It's undiagnosed. I just know I'm a good person. I want to get out of my company's hair. If would have been different if I applied for the job and mentioned on my CV that I had a diagnosed disorderas was accepted on those grounds. I knew I had anxiety and was strange, but I didn't think it would affect my performance.

So here I am. 

Everything just flipped on it's head other the last 3 weeks I've been signed off sick. I've been blocking so many things each day that confirm autism etc.

From my thoughts and to the way others interact with me. I can't do this anymore. Sometime people I don't know really want to talk to me at work and are very nice about it. I say 'Good Morning', but I can't engage in a regular conversation for long so I close it. There;'s a nice woman that works there that always says "Good Morning". I say "Good Morning". "Are you ok?". "Good thank you". We've had the same conversation for 4 YEARS!.

I see it all now. I see it.

My mother has said that it's showing the older I get, but my doctor said that it's harder to diagnose adults.

I don't want to think about it. I wish I could just do gardening at my mum's home and not get diagnosed, but I have to pay for things. I can talk for about 2 mins max. I've read that the formal autism assessment is something like 1.5hrs! That is absolutely awful. I don't want to be that exposed. All on tape.