Requirements on applying transit visa for uk?

i am a filipino citezen ,my brother in law is an offshore officer . he talk to a international offshore agency that could help me to get a offshore trainee job in UK waters and europe waters.i had complete offshore tranings and had a few experiance in onshore work only. he ask me to inquire what visa should i take ... ist the transit visa only due to i will be working in a vessel ship . what are the requirements and attachment documents do i need before i go to VFS Global to submit my documents for approval of transit visa at UK waters... ? i am very thankfull for someone who can forward me the requirements and attachment documents for this matter . tnx very much hope to gather some answer as soon as posible thank you