Latest guidelines suggest the queue will follow the path of the River Thames and possibly all the way to Southwark Park, with the line managed by more than 1,000 volunteers, stewards and police officers.
Tens of thousands of people are expected to join the queue from Wednesday, in what will be a major logistical challenge for authorities as members of the public gather in the capital to say a final goodbye.
How to visit the Queen lying in state
The Department for Digital, Culture, Media and Sport plan shows members of the public will join the line on the Albert Embankment, which will run behind the London Eye on to Southbank.
There, it will follow the river past landmarks such as the National Theatre, the Tate Modern and HMS Belfast, reaching “maximum capacity” at Southwark Park.
Under the arrangements, once mourners have passed through the Albert Embankment they will be directed across Lambeth Bridge and through airport-style security before entering the Palace of Westminster.
The queen's lying in state opens to the public at 5pm on Wednesday and will be accessible 24 hours a day until it closes at 6.40am on Monday – the day of her funeral.
People queue to view Queen Elizabeth II's coffin lying in state - in pictures
Metropolitan Police officers will be joined by volunteers and stewards, while toilets and water fountains will also be provided at various points along the route.
What are the rules?
A wristband system will be used to manage the queue, with those waiting in line given a coloured and numbered wristband that organisers said would be specific to each person and “strictly non-transferable”.
“Your wristband also allows you to leave the queue for a short period to use a toilet or get refreshments, then return to your place in the queue,” the official guidance says.
St John Ambulance members will be stationed along the route, while more than 100 Scouts aged between 18 and 25 will join volunteers from the charity Samaritans to offer help.
Lambeth Palace is also expected to arrange a multi-faith pastor service to provide support to those who need it.
The UK mourns Queen Elizabeth II - in pictures
Chief executive of the Scouts, Matt Hyde, called it an “honour” to play a role in proceedings.
Keith Leslie, chairman of the Samaritans, said volunteers would be there to “listen and support anyone who would like to talk openly about how they are feeling”.
The main queue has step-free access, the government said, with a separate accessible route also planned to run from Tate Britain, where timed entry slots will be issued for a queue going along Millbank to the Palace of Westminster.
Guide dogs will be allowed inside Westminster Hall, with sign language interpreters also on hand.
Venues including the Southbank Centre, the National Theatre and Shakespeare’s Globe will open for longer hours to accommodate those queuing, while the British Film Institute on the Southbank will do the same while providing an outdoor screen with archive footage of the queen.
Chief executive of the Southbank Centre Elaine Bedell said the organisation was “pleased to be able to play our part in providing a little bit of respite”.
Cafes and other businesses are expected to follow suit, while welfare centres will also be in place.
RAF plane carrying Queen Elizabeth II's coffin lands in London - video
The public are being warned that strict rules on bags will be in place, with those planning to visit Westminster Hall urged to plan ahead.
Once inside, the public can expect to walk past the coffin of the queen, which will be raised on a catafalque and will be draped in the Royal Standard, with the Orb and Sceptre placed on top.
Queen Elizabeth II's coffin arrives at Buckingham Palace - video
It will be guarded at all hours by units from the Sovereign’s Bodyguard, the Household Division or Yeoman Warders of the Tower of London.
Michelle Terry, the artistic director of the Globe, said the world-famous theatre will be open 24 hours a day during the lying in state, with the gates along the river adorned with a rosemary wreath of remembrance, in reference to Shakespeare’s play Hamlet.