If you are in São Paulo and need assistance such as replacing a passport or applying for a new passport then you can contact the British Consulate in São Paulo. You can obtain emergency travel documents at this consulate. You can also ask about a British visa such as a visitors visa or a for the UK. If you cannot obtain advice then contact the British Embassy in Brasilia for assistance.
The contact details for the British Consulate has been added below with a map and telephone numbers and other contact details such as email for them. See: Consulado Geral Britânico
British Consulate-General São Paulo
Rua Ferreira de Araújo, 741
Mon-Thu: 08:30am to 12:30pm and 13:30pm to 17:30pm Fri: 08:30am to 16:30pm