Here are some links to some other materials which you might find useful, some are specifically for the SNAB course whereas others are more generic on Nuffield websites.
Interview with Sarah Darwin for SNAB A2 Topic 5
Film about seed conservation from the Millennium Seed Bank
University biology courses and employment in biological sciences often require maths expertise beyond GCSE. SNAB students could consider taking a Free Standing Matsh Qualification (FSMQ) alongside their A level. Level 3 FSMQs provide UCAS points.
Here is a unit on the Free-Standing Maths site which gives help for SNAB students with Handling data.
This lesson on the Teaching About Science website is about evaluating the extent to which evidence supports scientific explanations.
Useful resources for teaching about ethical issues in biology.