PIP claim and evidence

hi, i have my PIP form and am filling it in. Am writing to GP for a letter to say I cannot attend a medical assessment centre for a face to face. I have an address that has come with the form that is ' PIP Post Handling Site B, Wolverhampton. WV99 1AA' Should I get the GP to put this at the top of her letter and put dear whomever it may concern. (obviously the envelope has to have my address so I get the letter sent to me first to add to my claim form)

Hi, i assume the PIP Post Handling Site Wolverhampton I refer to above is DWP address?

I assumed wrongly (did not wait long enough to see your reply) and posted my letter requesting GP to write a letter saying why I would find it impossible to attend a Medical Assessment Centre using the PIP Post Handling Site Wolverhampton address on the letter, I have made it clear the GPs letter needs to come to me to attach to the claim form thou. Do you think that ok?

I am getting supporting letters from two other sources too, I have been asked for addresses to head the letters, Although the letters will be addressed to PIP Post Handling Site Wolverhampton, they will still be sent to me to add to my claim form. Should I just continue , think it will cause confusion if I try to intervene these supporting letters that are currently being processed. I could put a line through the address at the top o the letters. I am confused how to get an address from AP, don t even know which AP and how to contact them, and would they know def which DWP address at this early stage