From Den Helder I did something quite similar but... opted for the non-stop option. Or at least, one stop, in Weymouth. I also did not have on board the entire family
(only my 15 yr old son), my good wife and younger daughter went by train to Cadiz, and did have on board an old trusted friend who is/was also extremely experienced.
But I only had three weeks including putting the boat
away for the winter, so couldn't plan indefinitely around the weather. And we planned only as far as Cadiz. If time is not an issue then a lot more options become feasible, which will probably revolve a lot around waiting for weather and around the needs of the family.
Having said all this, it is an absolutely amazing trip.