You can expect to be in NZ for 7 months initially, then you fly back to the UK for 5 weeks. These5 weeks are broken down into 1 week leave then 2 weeks revision at bristol then 1 week of exams at bristol followed by another week of leave then is back to NZ. The second phase of NZ is approximately 4 months long, after which you return to the UK and the first 5 weeks back are as before. Once the exams/leave is over you then go to bournemouth to finish your IR.
With regards to family in NZ, CTC are not fantastic fans of having partners accompanying cadets and I am unaware of their position regarding kids. If you take children then it is likely that you will have to fund your own accomodation as us cadets only live in single accomodation. They can occasionally squeeze a double in, but almost certainly will not get 3 people to a room. Obviously you would need to seek more detailed/personalised advice from someone at CTC before deciding on anything.
Hope this helps, if not then send me a pm and i'll try to help.
Ps Jordie
Yes it may hinder you in your interview, as they may question your commitment to the cause. For example if you fly long haul then you could spend quite alot of time away from home. It sounds really harsh, but flexibility is one area that you are assessed on throughout assessment. I had to convince them that I was prepared to leave my girlfriend for my training period!