Excellent result, not "not bad"!!! No, HbA1c and average glucose are unrelated. You shouldn't be told that they are related because they are not. I think we've got a different policy in the UK to other countries as we do not give out a patient's average BG with their HbA1c result.
HbA1c is directly related to the exposure that red blood cells have to glucose. If you were to plot a line graph of BG on the y-axis and time on the x-axis, then the area under the line (called Area Under the Curve, or AUC) is the exposure that the red blood cells have to the glucose. Sure, the average BG might approximate to an HbA1c value, but these vary wildly from person to person. An average will not be considerably affected by a few random highs, whereas an AUC calculation will.
Also, there is a natural variation in the lifetime of red blood cells from person-to-person, which will affect the HbA1c measurement. There is variation in the "stickiness" of peoples' red blood cells too. Finally, the HbA1c value is highly weighted to the most recent few weeks, where approximately half of it comes from the most recent month, around 8% from the most recent week and around 8% from month 3 to 4 - even though most people think that an HbA1c comes from your previous three months.
So, to give an average is misleading and I would expect better from healthcare bodies who insist on doing this.
Source: I work in pharma where I model AUC curves for oncology drugs.