I have lived in several places over the years.
I went to University (small town) almost 200 miles away from my home (large city in the North.) Returned home after Uni and started work. Met Dh, due to his job we moved 120 miles South. Stayed there for a bit, got married, had a baby and knew that the house we were in for the local schools was terrible. Lovely house, terrible schools.
Job relocation saw us move another 140 miles back North but still 70 miles from our original city to another big city. We even moved house locally for a secondary school!
I think you have to list what you love about where you are and what you would like. It is easy to not think about the actual specifics of why you like a place. How often do you visit your family and see your friends? We have friends in the South and we tend to travel to them because they are all close together and we can all meet up at one house. in 15 years they have only travelled to us about 5 times.
Dave Gorman said that he moved out of London and friends couldn't believe it but when he asked them the last time they had visited all the things they listed they hadn't been for years.
I have a larger house than I could ever afford even when we did the first move South. I am a SAHM, there are plenty of job opportunities for Dh, transport links are fantastic, we have a very comfortable lifestyle. I know comparison wise my 4 bed detached house costs 1/3 of what our friend's 3 bed semi detached house costs within the M25.
We have the most beautiful countryside, we have museums, theatres, galleries, parks but what we won't have is your family and friends but the further North you go the more friendly people are. We don't avert our eyes on the Tube (I may have caused havoc when my friend and I spoke on the Tube recently, we were unaware of the headphones in, eyes down, pack in like sardines customs of the Tube
)
As for the "outsider" bit, I talk to people from all over the country who have moved here, including from London and some from other countries. I was welcomed here too. Because your child is going into year 9, the time to jump is now before year 10. You could always rent your house out and rent wherever you are looking in case it doesn't work out.