I think your first route should be to visit each of the three cities which can be done very easily. See which you instinctively like the feel of. Next would also be to visit some schools. There are more options in the French speaking part I think. I personally wouldn't go for a "British" school but one which takes the best from the British system and other systems and integrates it into the international IB system - PYP (Primary years Programme)for your kids. There are a vast array of schools in Switzerland so I think that if you can go anywhere then visit some examples. Here's a
list of schools authorised for this programme:
Here's a list of all the schools in the Swiss Group of International Schools. Good luck and keep asking questions if you like.