You should be fine with the 16/17 material – what is really, really important is that you practice, practice, practice over and over again the mcqs and mtqs from those revision kits
Don’t write your attempted answers in the kits themselves – write your answers on a separate piece of paper. In that way your subsequent efforts will not be influenced by your earlier attempts
OK?
And, if you need to, post again on this forum and I shall answer any questions that you may have