There are some suggested materials here
https://www.elevenplusexams.co.uk/schoo ... ey-11-plusIt also depends how your DD best learns and is motivated. I found that ten minute tests worked to build up knowledge and confidence. Then every other month do a mock test or a full paper to work on timing and technique and get the bigger picture.
Newstead isn’t difficult, many girls come out of the exam saying it is easier than Kent or Bexley. The challenge is that it requires more accuracy and there are more questions that are ‘tricky’ - I.e there seems to be two possible answers and it is easy to pick the wrong one.