Thanks guys. Like I said, my husband is English and I've been all over England, but seeing it through the eyes of camping/backpacking is different. We just didn't know what was typically done. Sounds like wild camping is possible but it's hard to know how realistic it would be.
We're not looking to do any of the really long trails...just not that much time, and we have quite a lot of family to see. But we wanted to head out for a week or so at some point. Here in the US, that would mean a 40 mile trail or so (we're wimps). Train access at each end would be a plus.
Anyone have any specific suggestions for places that you've camped? Places that you know wild camping (LNT and unobtrusive of course) would work? We've got family all over, including Scotland, so we're fairly open to location. What about the New Forest? Is wild camping done there? Much family is in Hampshire, so it's close.