if my 2 hour post blood sugar is normal (around 5.8 mmol/l) would that mean my fasting blood glucose in the morning would be normal.?

First of all, my friend, ignore the response from Gary B. As with many responses he offers here, he is WRONG about this too. Diabetes CAN be diagnosed without having a HbA1c test done. i.e. it CAN be diagnosed by using fingerprick tests.

As for your question, there is NO WAY to know if your fasting blood glucose level would be 'normal' without having it checked. You COULD still be diabetic, or at least pre-diabetic, even if your two hours post prandial blood glucose level is within the 'normal' range. SOME people can have what's called Impaired Fasting Glucose, which means that their fasting blood glucose level would be higher than the 'normal' range, yet have it fall back into the 'normal' range once they become active throughout the day.

Yes.

the simple finger prick test CANNOT be used to diagnose diabetes.

You need to have the doctor perform the A1C Blood Test.