For an overview of tango events and classes in CHRISTCHURCH: 
http://www.tangochristchurchcalendar.org

NZ Tango Festival: http://www.nztangofestival.co.nz/

MILONGUERO style tango:
For classes in Buenos Aires - La Academia de Tango Milonguero: http://www.laacademiatango.com/content/quienes-somos
Practimilonguero Blogspot - includes video interviews with milongueros in Buenos Aires: http://practimilonguero.wordpress.com/

MUSIC:
Todo Tango - for info about the tradition, orchestras and musicians: http://www.todotango.com/