I visited last month. Here are some things to keep in mind.
- You can check cloud cover and aurora intensity at
Aurora forecast for Iceland | Aurora forecasts | Icelandic Meteorological office ... but also have your stuff ready to go at a moment's notice
- Keep your spare batteries warm by putting them in an inside pocket of your jacket / fleece / sweatshirt.
- Be mindful of condensation when bringing your camera into a warm car or hotel room. I put mine into a neoprene case and wrapped it in my shell jacket before taking it back inside (would have zipped it into my backpack, but I rushed outside for the aurora and didn't bring it).
- I used a Rokinon 16mm f2.0 at night.
Sample
I had a fantastic trip. You and your fiancé are going to have a great time!