Blog by a Biology teacher, aimed at IB students but great for A level too, lots of links, videos, reviews, things to think about here.
Biology revision notes for the IB – but covering a lot of the same topics as A level
Online tutorials on many aspects of A level biology (US site)
Animations and diagrams on cell and body structure, along with some quizzes – bit of a strange site but contains some useful information
Really useful site if you want a straightforward and easy to follow list of differences between pairs of things – e.g. DNA and RNA, artery and vein.
Many MIT courses available, free, online. This link is to “Fundamentals of Biology” but there is much more available here, video lectures, resources etc.