You sound as if you are not totally in agreement with the move. I think my husband was a bit doubtful when we moved to our smallholding 26 years ago, but it has defined our lives forever and he would never leave now, so try to look at the positives. You have children - children usually love a country life, country school, wildlife, growing stuff. It depends on the ages of your children of course
It's hard to say how to deal with your new garden when you haven't chosen the property yet, but my advice would be to give it a full year, so you can see what's growing in the garden and on the farm, which weeds grow, which plants are already there, what the climate and local weather is like, which direction the weather comes from mostly. Give yourself that time to learn about your new property before taking any drastic steps to rearrange things. Maybe concentrate on redecorating the house to your preferences.
I think it's always a great idea to buy a few good books on gardening, veg growing and smallholding in advance so you have a pretty good idea of your direction before you start.
I hope you come around to loving the idea, as everything will go so much more smoothly if you and your whole family are together in your plans and enjoyment.