Hi Nicholas - Sorry to hear your diagnosis. My mother-in-law lives in Capetown - SA is such a beautiful country.
I got AN diagnosis in April (1.4cm). I joined ANA as a member, and I have found the many webinars posted in the members-only section to be really helpful, and the newsletters are very well written too, with a good medical article as headline in each issue.
At 3mm, you should have a lot of time to research your options. Of course keep up with the MRIs because ANs can have growth spurts / not follow the "1-2mm / year" average.
At 39 - some would say you are too young for radiation, that there is not enough data yet on long term outcomes. Others would say it's an excellent option, seems like the % of people choosing radiation over surgery is steadily increasing. You'd need doctors' opinions on the specifics for your case as to what to expect. Different docs may recommend different things based on their own areas of expertise.
You will see, AN patients also have their own point of view on radiation, surgery, or observation - for small & medium ones, the patient has to make the decision, which is really hard !!! I'm 54 and will be having surgery not radiation.
I googled and saw this place in Joburg - looks promising?:http://www.entinstitute.co.za/A_aboutusBio.asp
Also here is a doctor in Los Angeles who is from Joburg originally - he specializes in neuroradiology: http://www.micsc.com/bradley.html
maybe you can email Dr. Bradley, and he may have insights on what's happening in SA, for AN treatment.