Hi there, and welcome to the forum!
It sounds like you're stuck on the portion of trying to make sure the users are selecting valid options, rather than actually making the VLOOKUP work right now?
Form controls can work (I have a basic article on using them here), and can certainly help you with implementing any of them.
Personally, though, I actually like using data validation lists in many cases. (Data-->Data Validation). Set up a list, and point it to a range of valid options.
I've attached an example using a Data Validation list to drive a VLOOKUP for you. Let me know if you would like any help in adapting it to your situation, or if you'd like to pursue form controls instead.