The receptionist has no right to know what you're there for.
When they ask, I take pleasure in replying 'I will discuss that with the doctor.'

I'm clever enough to know a. whether the practice nurse can help me and b. that the practice nurse would probably send me to the doctor anyway.

I haven't always been this clever. A few years ago, after a traumatic event, I rang for a doctor's appointment because I was completely dazed and stressed.
Caught offguard, I told the receptionist why I was ringing, and was told 'You don't need the doctor for that. You're not ill.'

A while later, when I did manage to see the doctor, I told him this. He took note and the receptionists were soon treated to 'retraining', including, I inferred, an almighty bollocking.
(Juan Quar is clinging to her front teeth on, Fri 28 May 2010, 9:48, Reply)