I'm travelling from India to Canada and I have Canada visa with me. I haven't buy ticket yet. I want to stay 4 to 5 days in United Kingdom. And I'm planning to buy British Airways ticket which has 1 stop at LHR.
The UK does issue a special category of Visitor in Transit visas, but they are only for stays of at most 48 hours.
For a 4-5 day stopover you'll need to apply for a Standard Visitor visa, which costs £87.
(That's if you need a visa for the UK in the first place, of course -- I assume so, since otherwise you probably wouldn't have asked, but I don't know since you haven't told us your nationality).
