I used the Sage Instant payroll self study workbooks, in conjunction with HMRC helpbooks downloaded from their website. They are very good and go through manual payroll as well. I think either the Sage Instant or Sage 50 will be ok, although I have heard that the Sage 50 payroll doesn't print one of the reports that is asked for in the exam, but that people have managed to get round it.
And there's always this friendly bunch on here for help :)