pavmas
Unfortunately, participating in WFIs is a mandatory requirement of being in the WRAG.
You can try contacting the JC+ advisor handling your case, as you are appealing the may be willing to defer the appointment, alternatively, it is possible for the interview to be held over the phone and on occassion at your home, although the latter is very rare.
When you asked for your paperwork, was this over the phone or in writing? At the first, I would suggest you phone them to find out what is going on, and then if necessary make a Subject Access Request, see page 12-13 of the ESA Appeals guide.
www.benefitsandwork.co.uk/help-for-claimants/esa Gordon