I'm a Sri Lanka national and traveling to Bahamas. The route is Sri Lanka (Sri Lankan Airlines) to Heathrow (British Airways) to Nassau. Sri Lankan airlines will arrive in Heathrow around 4PM. The flight to Nassau from Heathrow will be the next day at 11am.
Sri Lankan airlines will arrive at Terminal 2 and I need to go to Terminal 5 to take British airways next day.
Do I actually need a transit visa? I researched this and got very conflicting answers. Some people say that you don't pass through immigration from Terminal 2 to Terminal 5 etc.
If I actually need one, which transit visa do I need? DATV or Visitor in Transit? Does the DATV allow staying in direct air side until next day?