My preparation for AS exams consisted of doing many many practice papers,including the solomon ones, they are just practice papers produced by some company (not sure that its the exam board) which are a very similar format to the exams themselves. IN my opinion they are very useful, they allow you to get up to speed on the questions, time yourself etc etc etc, there are loads of other companies that do past papers too, for C1 I found more than 20 papers.... if you look on the forum u'll find the links. Anyways solomon papers - yes in my opinion it is good practice to do these.