No, they will call you. Even if they call you please remember that GP's sometimes need to discuss things they find even if they are not serious and receptionists can't give details for obvious reasons. That tends to worry anyone.
I know it takes 48hrs according to the nurses at our blood testing clinic. That's just the testing though, the surgery will then be adding time to look at it.
If it comes back all clear then it's just back to your GP really. They will decide if something more is needed or it might just be no further action or monitoring.
If there is nothing in a test and you aren't due to have a follow up, they may not even contact you.