A valid referral is only required if you wish to claim a Medicare rebate to see a psychologist, dietician or psychiatrist.  

Referrals to a psychiatrist:

Referrals to a psychiatrist can be made by a GP or other medical practitioner

Referrals to a psychologist:

Referrals to a psychologist may be obtained from either a GP, psychiatrist or paediatrician.  Referrals from a GP are known as a Mental Health Care Plan. You will need to speak to your GP to see if they feel you are eligible for a GP Mental Health Care Plan.  You can only receive a maximum of 10 Medicare-rebated psychology sessions per calendar year.

Referrals to a dietician:

Most private health funds offer rebates for Dietitian consultations. Rebates depend on your level of private health cover; please contact your individual health fund for more information. Patients who have been referred with an EPC plan from a GP are entitled to receive a Medicare rebate of $52.95 each session they are referred for.

The frequency of your appointments will be based on a number of factors, but primarily by the severity of your situation.  Your clinician will make a recommendation about the frequency of appointments during your initial appointment.

The amount of sessions will depend on the presenting issue and background.  Your individual needs and requirements will be discussed and determined with your clinician.