I guess you would be making the right move for all the right reasons. Your children's education and future should be first on your priority list. When we were going to buy our house, we didn't really want to pull the kids out of thier school (as it was a good school anyway) so we payed a bit more for a property in the same area even when we had cheaper offers elsewhere. By the way not everyone has the luxury of living close to family. And the likes of us who don't, have managed very well without them. If you had to choose, which would you go for?
(a) seeing your family everyday, while your children stay at home cos they can't get a good sec school around
(b)Have your children enrolled in a good school close to home, and seeing your family occassionally. (remember your family are only a phone call away)
I would definetly move away from family if it means my children getting into a GOOD school. Your children are not only your future but also the future of the nation. Good Luck with your decision.