About a year after I moved here, I got a letter from NHS Scotland, doing an audit of their records and requesting information from me that I was indeed eligible for the NHS. I can't remember exactly what I had to fill out as that was about 3 years ago- but I think they needed a copy of my work permit and visa. I think for date intended to leave, I put something like 'visa valid until Dec 2012 and will reapply' So yeah, pretty normal stuff I think.