The problem with the A.’.A.’. is that they are divided into “lineages.” I myself couldn’t tell the difference between their teachings so you might as well pick the one that seems most convenient. Out of the four lineages that I could find two actually responded to emails. The branch out of the UK can be reached by writing the Chancellor at Chancellor@aa-thelema.org. The one based out of San Francisco can be reached by writing the Cancellarius at cancellarius@onestarinsight.org. Either one has members spread out through the US and other countries centered on major cities.
Good luck.