Why does any healthy adult need a 3rd dose of any vaccine a month after their 2nd dose? In his early 60s, had 1st dose start of May and 2nd dose last week of July at a GP. Then decided he wanted more protection so exploited the poor Pharamcy controls loophole to get a 3rd dose in last week of August.
This same guy is a Kiwi and as soon as he can return there without HQ, plans to go and get 2 Pfizers there. Its overkill.
There is a case for boosters 6-9 months from 2nd dose and I will find a way to get a Pfizer or Moderna one for sure.
However, nowhere in the world is recommending a 3rd AZ dose 1 months after the 2nd, unless there was a screw up with dosage.
But hey if you want to get a third AZ one now, there is no chekcing in place to prevent it if you go to a walk in chemist. Knock youself out, there is plenty on doses available.