I did a few Bond Assessment Papers (4th or 5th). I also found a few grammar and indie school maths papers from different areas, online.
I think that the papers used are written by the school, so you really don't know what will come up or what the format is (although it is multiple choice). It is supposed to only contain maths that they have covered in school but I think some of it, may not have been taught yet (but will be taught by the end of year 6)
Good list of maths revision topics
http://www.elevenplusexams.co.uk/revisi ... _maths.php
Maths revision aids
http://www.elevenplusexams.co.uk/revisi ... wnload.php