Late notification of UC migration

Received my notification today of UC migration however it is a reminder not the original letter. The original was not received and there was no text either. Discussion with the helpline has been unproductive and an exercise in data gathering only with one male asking for personal data to provide the national citizen advise bureau number when I asked for his name he hung up. I effectively have a month to apply, research what needs to be done. The call handlers were eager to transfer me today to the telephone application department despite me saying I was not sure how I wanted to proceed. Further can anyone tell me if the online process is disability friendly, I have been told it is standard website. The call handlers are inconsistent about what needs to take place, one said no grant of extension, the next says it is possible but closer to the deadline, the third says a recently expired passport can be used. Can someone clarify these points? Thanks.

I note that transitional payment is lost if you do not start a claim one month before the deadline date. Are there any exceptions to this situation, say when requesting extra time due to disability and not receiving a notification before a month of the deadline?