Pip Tribunal postposed due to Doctor not available

No, I doubt that very much. As long as additional information was provided within the 14 day timescale, then it will be admitted as supporting evidence. The doctor not being available. I have heard of this before. The reason that time, was something to do with the partner at his own surgery being taken ill had he had to handle the work load. (Cannot swear to the reason) However, my friend, to whom this happened received another date within 28 days, and all went well. Good luck, and try not to worry too much.