I had my hysterectomy in December so I haven't had my first vault smear either. I did understand from my Consultant though that it would be like a regular smear except they would take cells from across the top section of the vagina. He assured me this was routine but necessary as cc patients do have a slightly higher risk of vagina cancer ( when compared to the general healthy population). A small increased risk but never the less needing a precautionary routine regular check. My vault smears will be yearly for a couple of years and then the time in between will revert to the regular smear timetable if results are good.
Hope this helps. Love to know how you go so I know what to expect!