Best of luck with the move
I have lived here over 20 years and still love the place
I also have a son who is aged 16, my daughter has just turned 13.
As for schools Twynham is fantastic as a secondary school, the headmaster is just massively enthusiastic towards the the school in every way and I guess this must rub off and follow the ranks down to its pupils.
You will not be disappointed with move to Christchurch.
Best of luck