The BBC show is very useful to look at as an example of the contemporary horror production. Postmodern to its core with characters questioning all the traditional cliches of horror roles even as they live them, aimed at a broad 15-34 (despite the post-watershed timing its 15-rated by the BBFC) youth audience, with characters and plotlines to attract both genders, infused with humour to leaven the horror, and with its own online-only spin-off or companion series, it truly is 21st century horror.All the episodes from the latest season (S3) are available on iPlayer as I write.
You will see that moral issues and debates are rehearsed through the issues and disputes; the situations (dis-equilibriums if you like) the protagonists get themselves into, and the efforts and attitudes of the antagonists they face. Horror has always been a platform for exploring moral codes and issues, not just a means to shock and appal; titillate and terrify.
In S3 Ep2 we see a great example of the representation of age - a teen vampire who starts out as the amoral teen thug of tabloid headlines but, through the episode's narrative arc, is transformed when given a chance by initially dismissive adults.
In S3 Ep3 we see a great exploration of the zombie - worth looking at for various reasons. Watch it to see how vital a role sound plays; the zombie is only made truly disgusting and horrifying with the overdubbing of bones cracking and rotting flesh 'sloshing' - strip these away and even with the effective music the zombie lacks verisimilitude; fails to convince let alone scare. Furthermore, as always with zombies, the character is a metaphor for part of the zeitgeist (the spirit of the age; common features or values of our time): the wealth-obsessed WAG, and the focus on celebrity culture and material goods/brands in the 21st century Western world. Critics of globalisation (an issue we look at in A2) argue that our media, from hip-hop videos to the various national editions of Hello magazine, are a conduit for spreading these vacuous, empty values across the globe.
As a UK TV drama, looking at and applying the semiotic terminology and framework of analysis is useful for your AS exam, and work into A2 Media (this technique lies at the core of all Media Studies work across the 2 years).