Hi Forrest
First of all i would advise that if you are a union member that you contact your branch. They have an obligation to the membership to assist members in areas exactly like this.
However the procedure would be the Ill Health retirement procedure 2009 that Royal Mail will operate by. What ever your intention you need to start the process again with ATOS, yes there the annoying calls intially, but for more serious cases face to face consultaions are arranged. ATOS are the people who based on your medical info and history will recommend to RM whether you are able or unable to continue fulfilling your duty. Whatever they say if you do not agree there is an appeal procedure, so i.e. lets say you want to jump ship, cant blame you but ATOS say you can do something, if your own GP or medical professional suggests otherwise then you would have a good case.
Whats also important in such cases like these is to raise the issue both with your union representative and then ATOS about DDA - Discrimination Disability Act. If you fall into the category of DDA then RM have to treat you extra special. But only again can ATOS recommend that this would be the case.
If you are offered ill health then there are 2 different kinds. One is a recognition that you are totally knackered and would be unable to perform any work anywhere and this would be ill health with immediate pension. The calculations on this vary depending how many years in service and how many years fulltime/partime paying into the pension. The second option is where you're assesed not fit to perform any duties that fall within your workplace or near locations. However this recognises that you would be fit to fulfil employment in an alternative industry. This option is ill health with lump sum. I believe its 34 weeks pay but again there are other calculations that will be considered i.e. annual leave to take or not.
again i cannot stress enough - contact your branch or representative - don't put off.
all the best