Novels:

The Race of Scorpions (2012)

Torchwood:

Almost Perfect (2008)
Risk Assessment (2009)
Department X (2011) (released as audiobook only)
Ghost Train (2011) (released as audiobook only)
First Born

Doctor Who

Dead of Winter
Summer Falls (Doctor Who ebook written as Amelia Williams)
Being Human
Bad Blood (2010)

Radio Dramas:

Torchwood:
Golden Age (2009)
The House of the Dead (2011)

Audio dramas:

Doctor Who:

Dead Air (2010)
Art of Death
The Hounds of Artemis (2011)
The Time Museum
The Last Post
The Scorchies

Dark Shadows:

The Doll House (2010)
The Poisoned Soul (2011)
The Crimson Pearl (2011 - with Joseph Lidster)
The House by the Sea (2012)

Short stories (Doctor Who):

"Indian Summer" in Short Trips: Snapshots (2007)