Ex Practice Manager here .... in addition to the comments above regarding disclose of information to aid triage, staff being bound by GDPR and the 'turnover' of patients meaning that there's little opportunity to 'nosey', I'd like to add that a responsible and well run surgery should require all staff to advise the Practice Manager / Deputy Manager as soon as they become aware that someone they know is a patient there - be it a relative, friend, neighbour or acquaintance. The PM is then able to block access to those records for the staff member concerned, ensuring that information can't be seen, whether that's in the normal course of their duties, or, a deliberate decision to glean information the staff member had no legitimate reason to seek out.
The latter would be, of course, a disciplinary issue and should anyone fear their confidentiality has been breached in this way it should be flagged to the PM so a full investigation can take place. The clinical system can be searched to find out who's looked at a particular record - this can't be done without leaving a footprint.
Similarly, as a patient, you are also welcome to ask that your record is hidden from staff members you know.
I do understand that disclosing some symptoms to a staff member of the opposite sex - or either sex for that matter - can be uncomfortable. I also appreciate that doing this within earshot of other patients can be embarrassing. Again, a good surgery should provide work rounds for this ... asking if it's possible to speak to a receptionist in a more private area for example, or writing down your symptoms.
Of course, some people simply don't want to provide any information at all. This is their perogative but as demand for appointments outstrips availability and therefore clinical triage is really the only safe and fair way to assess who warrants an urgent appointment as opposed to a routine one, those patients would automatically be triaged as routine because the clinician has no evidence to support them being seen urgently