Thanks for all the kind responses.
The school my husband is most excited about is in Hertfordshire, which I have heard is a bit cheaper than living right in London, although within commutable distance. Of course , my husband being the Londoner, can't quite imagine England outside of London, but financial realities might prove otherwise.
My husband has his permanet green card, and I understand that he can't be out of the US for more than 12 months, but that is not enough to ensure that a green card won't be rejected. I think because we plan to not sell our house here, we'll continue to file taxes in the US, and the reason we are in England (school) is specific and has a finite period that we should be ok. We've had friends (wife American, English husband) who have done likewise off of a greencard.
When we come over to England this weekend, the real purpose is to visit hubbie's family, and to visit schools. While I am not interviewing specifically for any jobs, I am hoping to make "general interest" inquiries just to get a general since of how much transport planners make, what the market might be, how I can make my resume more CV friendly, and what, if any, things I can do to make myself more marketable.