F2F first medical assessment

Hi
Sorry if this has already been discussed. I sent off forms for PIP beginning of December 2018. I have a date for the F2F medical next week.
Since filling in the form my condition has got worse. I'm at present waiting for an appointment to see a thoracic surgeon.
I do have letters stating that I'm waiting for referral. I'm going to take the letters. My question is will they use the letters to update my claim? Thank you

Thank you Gordon. I'll let you know how it goes. Thank you for all the hard work you do