People who wish to see the Queen lying in state have been warned of long queues and banned from taking photographs.
Extensive rules and regulations were published before the coffin was flown to London on Tuesday.
She will lie in state for four days in Westminster Hall before her funeral on Monday.
More than 30,000 people viewed her coffin at St Giles' Cathedral in Edinburgh, where she lay at rest for less than 24 hours.
Hundreds of thousands more are expected to pay their respects in London.
The Imperial State Crown and a wreath of flowers will be placed on top of the coffin.
At 2.22pm on Wednesday, it will be taken in procession by gun carriage from Buckingham Palace to the Palace of Westminster, with the King, his two sons and other royals, as well as staff from the royal household walking behind.
At 3pm the coffin will arrive at the Palace of Westminster, where the Archbishop of Canterbury will conduct a short service.
The Queen's lying in state will then begin in Westminster Hall, codenamed Operation Marquee, and last four days.
Her closed coffin will rest on a raised platform - known as a catafalque - inside the hall.
The public will be able to file past 24 hours a day until 6.30am on Monday, the day of the funeral, which will be a bank holiday.
What should you expect if you visit?
Big crowds are expected, with warnings of long queues and delays on public transport.
Visitors will go through airport-style security and there are tight restrictions on what you can take in.
People will need to stand for many hours, possibly overnight, with very little opportunity to sit down as the queue will keep moving.
"Please consider this before you decide to attend or bring children with you," the official guidance says.
The queue may also close early to ensure as many visitors as possible can enter.
What can you take in with you?
There will be a strict bag policy, with each person allowed one small bag only.
The bag must be smaller than 40cm x 30cm x 20cm, with a simple opening or zip.
Anyone who has to bring a bigger bag will have to leave it in a bag drop facility - but space is limited and there is no guarantee of storage.
There are limited places to buy food along the queue route, so the public is encouraged to bring food and drink. But these must be consumed, or disposed of, before entering the palace.
A portable mobile phone charger is advised, given the lengthy queue times.
What items are banned?
Flasks or water bottles are banned, unless they are clear.
Flowers and other tribute items, including candles, soft toys and photographs, are also prohibited.
Flowers only should be taken to the dedicated area in Green Park.
Sharp items, paint sprays, padlocks, chains, climbing gear and any other hazardous items are banned.
Banners, placards, flags, advertising or marketing messages are also not allowed.
All camping equipment - including coolers, hampers, sleeping bags, blankets, folding chairs - are not to be brought, as well as non-foldable pushchairs.
Will it be accessible?
Step-free access will be available for those who need it.
How must you behave?
People are warned to "respect the dignity of this event", and remain silent in the Palace of Westminster.
Antisocial behaviour, including queue-jumping, excessive consumption of alcohol or drunken behaviour, will not be tolerated and people risk being removed from the queue.
People are warned to not film, photograph or use mobile phones in the security search area or within the palace.
Wristbands will be given at the end of the queue and only those with wristbands can stay, so people will not be able to queue on behalf of others or ask people to queue on their behalf.
You cannot bring tents or gazebos, or light barbecues or fires.
London should be dry from Wednesday until the funeral, the Met Office says, with less than a 10% chance of rain.