I would think that your starting point would be to look for jobs in the general area that you are considering, then look at the best options for housing/schools to fit in with what employment you get.
It is a hard one really, I have relocated a couple of times, but that has been driven esentially by a change of job and then I have worked everything around that - e.g. somewhere convenient to travel to and from my job. The time before last, we moved and then realised that although we liked the house and estate we lived in, we were really not happy with the location and the town we were in. At least by that time, we had had a chance to see where we would prefer and then moved again!
Try looking at upmystreet.com for info - there is loads on information available on the web.
You also need to think about your lifestyle and what you enjoy and don't enjoy about where you are now and what things you would like access to e.g. shops, cinemas, countryside walks, football clubs etc - that may draw your ideas closer to a particular spot. You might want to involve the kids about what is important to them as well.
A hard decision to make, but make it with your eyes fully open about what you are moving to, rather than just jumping in to anything.