Try exploring the following links. Some are useful for particular topics, others for general biology and some are useful for revision.
KS3 Links
KS4 Links
http://darwin-online.org.uk/ a useful site to discover the origins of Darwin's work
KS5 Links
http://www.sumanasinc.com/webcontent/animation.html
http://science.nhmccd.edu/biol/ap1int.htm#metab
Useful animations for many AS and A2 Level topics
http://www.cellsalive.com/
Useful for Unit 1 work on Cells
http://www.tvdsb.on.ca/westmin/science/snc1ap/snc1ap.htm
Useful for Unit 1 Organelles, DNA replication and Mitosis
http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a1.html
http://207.207.4.198/pub/flash/26/transmenu_s.swf
are useful tutorials for Unit 1 Transcription and Translation