If you wish to speak to a clinician over the phone for advice, you can request this via the receptionist. They will take as much detail from you as they can and put the request through to the relevant clinician. That clinician will then return your call.
If it is a medical emergency reception staff will ask you for further information, and will handle your call appropriately. In some circumstances you may be asked to dial 999, in other cases the on call GP will be contacted to deal with you directly.