Is your class over? In which case it probably doesn't matter what you do with your notes.
There is the Excel Edition of TW, that will convert your xls file into multiple tiddlers.
Why would you want to do this?
Right now, if you search for a term in your TW, it will just return the name of the tiddler with your 400 entry table. Not much more useful than using paper and pen.
But if you slice it into tiddlers, then when you search you'll find the actual items with your information.
Just my 2c