English Revision
http://www.bbc.co.uk/education/subjects/zv48q6f
http://www.educationquizzes.com/ks2/english/
Maths Revision
https://www.mathsisfun.com/ (good for revising formal methods of calculation, including fractions)
http://www.bbc.co.uk/education/subjects/z826n39
http://www.educationquizzes.com/ks2/maths/
https://uk.ixl.com/math/year-6
https://www.mathsgenie.co.uk/primary.php
https://www.maths4everyone.com/pages/ks2-sats-practice.php
Past Papers
https://www.satspapersguide.co.uk/ks2-year-6-sats/ks2-year-6-sats-papers/ (past papers with answers)