Jim
It is not unusual for claimants to have to re-arrange a PIP interview because it is inconvenient or to far for them to travel. You will however, need to attend the next one as you will only be given two opportunities to attend.
Have you spoken to your GP about the possibility of a home assessment, you will need them to write to the Assessment Provider on your behalf. The decision still lies with the AP, but this may make it easier for you.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems