Are you for real right now? LTC is cake compared to retail. You are over-prepared as it is. To "prepare" for LTC all you need to do is develop a super petty attitude about everyone and everything around you and develop those griping muscles so you don't get fatigued too early on in a shift. Also you need to train your thighs and butt to sit down for long periods of time without getting cramped or uncomfortable. It would help if you could spontaneously forget everything you ever knew about answering a phone or even the most basic problem solving skills.
I kid. Knowledge of IVs will be the hardest thing for you to pick up and it will come with time. Just ask your coworkers what they use as an IV reference and learn to use that quickly and efficiently. No one will expect you to be an expert overnight. You might think Beer's List or geriatric knowledge in general would be useful, but it's not. LTC is mostly about checking orders quickly and safely, same as retail but with far ore help and far fewer distractions. Assuming you come from a traditional retail experience you will love it. If you are anything like me the hardest part will be putting up with techs who fill less than 15 scripts an hour (not kidding) complaining about how much work they have and how it isn't fair, etc etc. 🙂
And congrats for getting out of retail!