Nikki left Hurtwood in 1993 and went on to study at LAMDA. Her theatrical credits include Twelfth Night (Bristol Old Vic), World Music (Crucible Theatre, Sheffield and Donmar Warehouse), Top Girls (Oxford Stage Company), Doubt: A Parable (Tricycle Theatre) and A Midsummer Night's Dream, The Tempest and The Servant of Two Masters (Royal Shakespeare Company).
Her film credits include The Omen (2006 remake), Cargo, and Almost Heaven as well as the screen adaptation of The No. 1 Ladies' Detective Agency.
Television credits include Bad Girls, Five Days, Holby City, Casualty, Spooks, Robin Hood, Canterbury Tales, The Line of Beauty, The Last Enemy and Torchwood. She currently plays Samantha Willis (the last surviving member of the government) in the BBC apocalyptic series Survivors and also stars in the BBC adaptation of Andrea Levy's award winning novel, Small Island.