Epigraphs are like little appetizers to the great main dish of a story. They illuminate important aspects of the story, and they get us headed in the right direction.
"Britain is proud of its tradition of fleeting [sic] persecution and conflict." – from Life in the United Kingdom: A Journey to Citizenship (UK Home Office, 2005)
According to its website, "the Home Office is the lead government department for immigration and passports, drugs policy, crime, counter-terrorism and police." It publishes Life in the United Kingdom, which contains the information that immigrants will be tested on for the UK citizenship exam. Chris Cleave chose this quote because of the error it contains. He explains,
[Life in the United Kingdom's] summary of British history is rather selective, and the work as a whole is riddled with inaccuracies and typographical errors. My belief is that if a refugee is prepared to walk away from a regime that has imprisoned and tortured her, flee to the UK, apply for asylum, and commit to memory the contents of the text book we make compulsory for her, then for our part we should at least be prepared to have that text book professionally copy-edited. The typo in that opening quotation is a nice example of a bureaucracy that is pretending to care, but not pretending very hard. (source)
Besides offering a good jab at Life in the United Kingdom, the epigraph also points to the novel's interest in and experimentation with the different ways English is spoken. It presents us with a running debate over which English is the "right" English to use among so many varieties. We see Sarah constantly trying to correct Charlie's English (as so many parents do).We see Little Bee using the Queen's English with razor sharp precision, all the while bemoaning the beauty of the Nigerian English she gives up using in an attempt to survive life in the UK.
In addition to the language issue, the epigraph helps prepare us for the unflattering light the Home Office is cast under in the novel. Cleave isn't just writing fiction here, but addressing what he views as major flaws in the way his government treats asylum seekers and immigrants, from detention centers where they're imprisoned to the quality of the material they receive in order to study for the citizenship exam.