Inside HegartyMaths we have an AS transition course that we advise all schools to run. This can be downloaded from our useful resources page. 150 of our skills can be set as AS transition work and this has proved a fantastic step towards AS level (students should complete all these at 100% before 1 October of their AS course.
Students are also able to access this document through their help and resources page under their names in the top right of the site.
Otherwise, our old site has hundreds of A-Level videos (as you can see below) but HegartyMaths is Y6-Y11 (+ AS transition).