Best way to validate these cells?

Hi there, I need some advice as to which would be the best way of proceeding.

I'm trying to set up a spreadsheet that will only allow certain entries in certain fields. For example, first column is 'C reference' and the only available options are C3, C6 & C8. For this, I have used Validation to pick these from a list that is listed in the top 3 cells above the first column, and these rows are hidden. This works fine. However, I now need the 'Switch' column to display about 25-30 choices in a drop down box. I could do this a similar way, but I don't think it will look so professional. Any advice what would be the best way of doing this would be grand, cheers.
I've attached a copy of the document so you can understand what I'm going on about.
Thanks.