"So what, just relocate? What if you live near family and want or need them to be involved? Or if you live in a HA house? Or if you just can't afford to move? What if you do all the preparation and then get made redundant or get relocated by your job?"
No. Not just relocate. No one is suggesting you do it in the next month. But you have got nearly 5 years to make plans.
Even in a HA house, you can change houses, ask for a different area. Does take time, but most people get a different house in a different area eventually.
You may have to make some compromises but it depends what you want. everyone has to compromise on something.
if you really do need to do rely on your family then that's your choice, you could slowly facilitate a new job? put your children in childcare and live off less? but if you don't want to, if you want parents involved, / need them, then you have to compromise on maybe sending your children to the school that is not your first choice.
there's allsorts of ways round it and it depends what you're prepared to do/ how important it is to you/ how much you are prepared to compromise.
If you get made redundant you might have to change jobs or change houses anyway irrespective of children and whether you like their school.
And finally, if you can't do anything at all, you just accept: okay this may not be ideal, but it's okay / it's good enough and I have no other way of changing it. so, that's it and just acceptance.