GPs are asked to complete lots of forms / paperwork on behalf of patients. Please do NOT book an appointment for this. This, along with specific types of medicals, is not funded by the NHS and as such is classed as private work. You should hand any relevant paperwork into the reception along with your contact details. The surgery will get in touch with you once they have reviewed the paperwork, ascertained what is required and worked out the relevant fee.
The GP cannot do this type of work during a normal consultation as surgeries are for clinical issues only.