Flutter-by
You can but it may delay your claim significantly.
Providing this is the first appointment that you have received then you can move it, I would say that you must have someone with you due to your conditions and no one is available to be with you on that date.
Try and make the new appointment while you are on the phone or you risk the new one being inconvenient as well and you will not be able to move this new date again.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems