Contacting doctors etc about PIP

On the PIP 2 form it says: Do not approach your GP to ask for a report as they may charge for this.

However, I wanted to speak to a doctor about applying for PIP because the doctor I used to have who knew all my history has retired. I've had an autoimmune condition and fibromyalgia for 13 years. In recent years, I haven't gone to the doctors about this because there's nothing much they can do. Do you think I'm OK to speak to them? The last doctor I spoke to was about HRT, I want to try to keep the same one where possible moving forward.

Also, I speak to my liver consultant every few months (unfortunately I had a call with him not so long back before I started my application for PIP), would I be OK just to let them know I'm applying for PIP or to ask for a statement?