UK National Curriculum Programmes of Study
The page linked to above has the complete National Curriculum documents for KS1 to KS4
For more guidance on KS3 Mathematics – see the KS3 page.
NCETM National Curriculum Resource Tool for Mathematics
National Curriculum Assessments KS1 & KS2 Sample Materials
Michael Tidd on changes to the Maths and English KS2 Tests
Note that documents are also available for each subject: