If you want to start your New Zealand tour from the South Island, departing from Christchurch is your best bet. It is New Zealand's second major international hub, where a lot of international flights will arrive and depart from.
Many tours depart from the Christchurch airport, but it's still advisable to arrive the day before your tour departure. This gives you a bit of flexibility if something was to go wrong with your flights, but also allows for you to recover from your jet lag before the start of your tour!
We have a huge selection of tours that depart from Christchurch. You can search for them based on your arrival / departure dates on our New Zealand tours page, or alternatively you can have a look at the tour options listed below.