Hi Rosan,
In view of your symptoms it is possible that they might test your blood for more than just HBA1C, so it would do no harm to treat it as a fasting test and not have anything to eat or drink (except water) for 10 - 12 hours before the test. If they are only doing an HBA1C then the fact that you fasted won't change the result in any way, but better to assume they may want to do other tests as well.
Incidentally the practice nurse will only be taking the blood sample, not performing the test. The testing equipment is very expensive and is used by specially qualified technicians, so the sample will be sent away to your nearest centre (usually a hospital), which is why the results take a week or so to come back.