I guess it's pretty tough for those without a family to envisage how much you will miss them and how much this in itself might affect your concentration and ability to focus attention where it is required. My personal thoughts are that you are better being out here on your own if you can be.
The schedule at CTC is quite a changable thing at the best of times (any cadet out here will be far too farmiliar with this fact!!) and this makes planning any down time very difficult. There is more time in the first phase to be away from the training centre than in the second NZ stint. It is quite normal in the second stint to do 5-6 10 hour days oper week when the flying is going smoothly and the lectures are in full swing. In fact we all just recieved an email today to tell us that we are to have 'standby' days when we are not booked in to fly where we must be contactable and available to fly at fairly short notice to make the most of available aircraft slots! Flexibility is not an ideal, it is a pre-requisite to coming out here (and no doubt for a great deal of the career path ahead) and you will need to demonstrate you are able to be flexible and focused throughout. When the family are around, it would probably make it much easier to turn down that extra flight or mass brief after a long day (although I am sure there are a number of cadets who feel the same way about the crate of beer sitting in the veg compartment of their fridge back at Clearways!).
It's all down to the individual. It will definitely be about 7 months out here in the first stint with a very busy and stressful 4 out of 5 weeks when back in the UK followed by about 3-4 months in the second stint and this may be too much time to be away from your children. Having them back in the UK waiting for you to return might just provide the motivation to push you through the course. Either way, you will need to think about your own accommodation at your own expense if you do choose to bring them out here.