OP, this is one of those threads where you ask our advice, we give it to you and your are choosing to ignore it. That's fine, your life.
If you are determined then Quinton House and Pitsford Sch are both very good private schs.
Areas to look at to live that I think may suit you best are :
The Brampton's
The Bringtons
East Haddon
Ravensthorpe
West Haddon
Hollowell
Creaton
Yelvertoft
Cold Ashby
Clipston
Have a look on Rightmove. Properties in these locations are not always available and don't often come up but keep looking and then you will be first in queue to view and act quickly to secure the house you want.
I live in one of the villages above and you may find that your £800k doesn't go as far as you may like to think so bear that in mind if you are planning to use some equity to fund sch fees.
I agree with some of the posters who suggest you may not see your family and friends as often as you think you might. You must keep that in mind and be prepared to throw yourself into village life. Be also prepared to do this but for little back. In terms of neighbours etc I have seen a grand total of 0 this year, despite the fact they live mere feet away from me. In fairness to them when we all happen to be leaving our houses at the same time , getting into our cars. You do get a friendly wave though that is about as much as they muster as they have their own, families, friends, lives etc and basically no time for me. If you like drinking tea and coffee with people you live near as a social pastime , put that to the back of your mind as it just doesn't happen! Unless of course you make the drinks at yours and people come largely to see what works you done to the house. Obviously you have said you already have friends and family here and I sincerely hope they do make time for you. I'm not sure how much social interaction you like ( I like loads and that's why I struggle here as there is none) but if like me you enjoy the company of others I hope your network up here make the time for you on a regular basis as they have said. If they work, have kids, clubs,hobbies, retired with new interests etc you may find they simply don't have have as much time for you as initially thought. If you are moving here to be closer to them and will rely on them on occasion for childcare/ support/friendship it may be advantageous for you to have that chat with them now to be clear in all your minds about what the others expectations are. I personally am busy but always make time for my friends and family, involving lots of driving and effort including hosting dinners etc but sadly many others don't so it all ends up a bit one sided. Just something to think about.
My kids were excited too when we moved here. In hindsight they were too young to really understand ( 6 & 12 ) However the reality soon hit them. My oldest has now just left as in his words 'this place is a dead ting' He has gone to university in Manchester and I doubt he will ever set foot back here again as we are moving anyway. I'm fairly sure he will build his life up there now as again in his own words "Manchester is brilliant"!
As others have said be prepared to drive everywhere as the bus network is non existent. That will include sch runs each day . If you are not in catchment or going privately there will be no other way to get your kids to sch. This becomes important if you are ill ,or Jct 15 of the M1 is closed as it is most days and you have been out somewhere more interesting than here and struggle to get back into the county. They still need to get to and from sch and I personally found this element the most restricting. Be prepared to get ur kids driving as soon as they can and factor in financing and funding their lessons and cars.
Also, the rubbish is only collected every 3 weeks but there is tip in Brixworth. I usually make a trip there once a month with my overflowing black bags as the one bin we are given is simply not enough for a families rubbish over a 3 week period.
However, if you leave your car windows open for a while the stink soon leaves your car. There is also a very good valet service up near Sixfields.
On a practical level place a chest freezer in an outbuilding as we have. Fill it with milk, bread and food etc. The roads are not gritted in the villages and you struggle to get anywhere. I understand due to cuts this year even more of the roads will not be gritted ( there is a full list on county website).
In the villages the electricity cables and water pipes are all very old and prone to failure. Stock up on candles!
WiFi is poor so if you need a good signal for work / kids games you will have to keep this in mind. Some villages do have Gigaclear but again the jury is still out on that one as to any improvement in service and it is quite expensive.
As far as I can see some of the villages have no virgin media etc at all,mine being one of them as companies can not justify the cost of laying cables given the small number of occupants. The only way to receive receive sat tv is via Sky. Alternatively Freeview with an Ariel.
Mobile signal is non existent so if you want to make mobile calls from home you will need to use a WIFi calling enabled phone. A land line here is also a necessity.
Most of the properties in these villages are oil based heating as no gas lines ever laid or connected. We have 4 oil delivery's a year and this is fine, no problem heating works in exact same way.
Hospitals poor and waiting lists long. They are also quite far in terms of distance from the villages. Although the above could be said for anywhere in the country. Private healthcare a must if you enjoy being alive and want to stay that way. There is a particularly good private hospital in Northampton I think it is called Three Shires but have a google yourself. I have used it and no complaints at all.
I hope your experience will be better than mine. As I said previously I know at least 10 other families who have moved up here over a period of 40 yrs, some with family and some without. All of them unhappy and in particular the older generation seem to struggle the most making new connections. If you will have all the friends and family you need up here, will see them often and be happy in that ,then this county will be a like a home from home and you should be ok.
Anyway, I am going to hide this thread now OP and won't be returning to it. Every time I come across it, it quite literally turns my stomach and reminds me what a total waste of my life the almost last decade has been. I'm moving forward now and looking to the future so I'm filling my head with those happy positive thoughts now.
All the very best to you and I am sincere in my wish for you and your family.