If you get a good GP there's absolutely nothing wrong with NHS care. It takes longer to get major things done than if you have expensive private insurance in the US, but since you'll only be here a year, then you don't really have to be worried about that.
As far as sticker shock goes, I used to live in southern California, and now I live in the South West of England, one of the more expensive out-of-London places to live, and I really don't think things are significantly more expensive here than in Cali. Others disagree, but I have a much nicer place to live for less than I would have had to pay there. The biggest shock is going to be the amount of tax that comes out of your salary every month. Since you know you'll be paying 40%, you will be able to prepare yourselves for that, but it still can be hard to get used to.
Brighton was just named the San Francisco of the UK by the Guardian newspaper, basically because it's very liberal and on the coast. It's also very touristy and studenty, however. The trouble is that you're not likely to know exactly what you want until you see it for yourself. Is there any way you could stay somewhere temporary for a month or two, and get a feel for things before you settle in? It would be a shame to choose somewhere sight unseen and then be stuck there if you don't like it.