Consultant Psychiatrist's Supporting Letter

Hi All,
I have sent away my DLA to PIP claim form but I am still waiting on my Consultant Psychiatrist supporting letter/evidence of my condition(s) They have promised me this will be done and I appreciate he is busy (I am not the only patient he see's) If I write my National Insurance Number and Name on the top of a copy of the above letter do I send it to the same address at Wolverhampton I sent my original PIP claim form?
Kind Regards,
Rob.

Thanks Gary.

Hi Gary/Moderators,
Excuse my ignorance, but when I send my Consultants Letter/Evidence do I have to enclose a covering letter explaining what it is or will the DWP know what to do with it from my National Insurance Number/Name on the top of the evidence/letter.
Kindest Regards,
Rob.

Thanks Gordon.