The plan also demands an increase of aid for public health and educational and cultural institutions such as museums and research centres. And it calls for the creation of "repatriation programmes" to help resettle members of the Rastafarian movement in Africa.
Martin Day, of Leigh Day, said he would request a meeting with European officials to seek a settlement, but would pursue a legal complaint if Caribbean nations were not satisfied with the outcome.
In 2007, Tony Blair, the then Prime Minister, expressed "deep sorrow and regret" for the "unbearable suffering" caused by Britain's role in slavery, but stopped short of a formal apology.
The British Government, which contributes about 15 million a year in development to the Caribbean, has consistently opposed financial reparations.
"The UK has been clear that we deplore the human suffering caused by slavery and the slave trade," a Foreign Office spokesman said. "However, we do not see reparations as the answer.
"Instead, we should concentrate on identifying ways forward with a focus on the shared global challenges that face our countries in the 21st century."