Like other novels of Victorian England, Charles Dickens's Great Expectations is didactic, seeking to awaken people to the need for certain social reforms. Perhaps, then, Dickens can be termed an author of the genre of social novels.
Among the concerns of Dickens were the plight of orphans and their mistreatment, the social evolution of the gamin [=street urchin]--Magwitch alludes to himself as one when he relates his life history to Pip--as a result of parents having died from disease or malnutrition or imprisonment because of debt. Certainly, the entire prison system of England comes under attack as Dickens often mentions Newgate and the underhandedness of lawyers such as Mr. Jaggers and the corruption of the court [Magwitch receives a longer sentence than Compeyson because he is in rags and Compeyson looks the gentleman]. Chapter XXXII in which Pip takes a tour of Newgate is especially poignant in its portrayal of the desperate and unjustly convicted.
In fact, Dickens viewed Victorian society itself as a prison because it was nearly impossible for people to escape the fate of the class into which they were born. Further, he made public appearances calling for social reform and was responsible for drawing public attention to many social injustices.
Indirectly, he contributed to a series of legal reforms, including the abolition of the inhumane imprisonment for debts, purification of the Magistrates’ courts, a better management of criminal prisons, and the restriction of the capital punishment.
In his social novels, Charles Dickens was, indeed, especially sensitive to social abuse--more so than many of his contemporaries such as Thackeray.
This is a slightly confusing question. Great Expectations by Charles Dickens is not really based on a model of Victorian Britain. Dickens himself lived in England in the Victorian period and wrote about life as he experienced it.
The sections about Pip's childhood are to a great degree based on the traumatic experiences of Dickens' own youth when his father was imprisoned for debt and Dickens ended up having to work in a blacking factory for several years, a job he hated. Later, Dickens worked as an office boy, and eventually obtained a position as a reporter by learning shorthand. This means that Dickens had first hand experience of life in England among the poor.
Generically, Dickens is considered a realistic writer, as opposed to a romantic, because he wrote about ordinary people and everyday life, instead of using exotic locales.