Jacir José de Souza and Pierlângela Nascimento da Cunha, who are from the Makuxi and Wapixana tribes, also hope to meet Pope Benedict XVI as they tour Europe in a bid to save their ancestral lands, which are under threat from large-scale farmers, reports Independent Catholic News.
For decades the Makuxi and Wapixana tribes, along with three other native peoples, have called on the Brazilian government to protect their territory, known as Raposa Serra do Sol, which is in the state of Roraima in the north of the country.
The Brazilian president, Luis Inácia da Silva, known popularly as Lula, granted official recognition to the Indian communities' ownership of the territory in 2005.
But a group of powerful landowners, who occupy a significant part of it, refuse to leave the area.
The Roraima State government supports the farmers, and is petitioning the Brazilian Supreme Court to give them a large piece of the Indians' land.
In recent months, the tribes have come under attack from farmers who have shot and wounded people, burned bridges and thrown a bomb into one of the communities.
CAFOD, the Catholic Fund for Overseas Development, an agency of the Catholic bishops in England and Wales, has been supporting indigenous groups in the Roraima region for many years. It is helping to fund this visit to the UK.
The aid agency works in partnership with the local diocese and the Indigenous Council of Roraima (CIR) which Jacir founded, to help indigenous groups secure the right to live on their traditional land.
On Wednesday 25 June 2008 Jacir and Pierlângela will meet Liberal Democrat MP Martin Horwood and officials at the Foreign and Commonwealth Office and ask for help to save their territory.
CAFOD's Head of Latin America, Clare Dixon, said: "CAFOD has been supporting indigenous groups in the Roraima region for many years to defend their lands, their culture and their livelihood. Now things have reached crisis point."
She added: "We are standing shoulder-to-shoulder with CIR to show the British Government that people living in England and Wales do care about what is happening on the other side of the globe and they should too."