Avoid the hassle of parking and relax on a Metro Bus. These run frequently from Christchurch. You can take the number 28 or number 35 (via Eastgate) from the Exchange.

Alternatively you can walk, bike, take the ferry from Diamond Harbour, or car share if you have to drive. Consider arriving early and spending the day in Lyttelton - there will be plenty to keep you entertained. 

Bus timetables and information on fares are on the metroinfo site.