Churches and cathedrals outside the capital are setting up large screens or television sets that will be linked up to Westminster Abbey so congregations can get together and share their grief.
The BBC, Downing Street and the Stationery Office have installed 16ft by 12ft screens to carry the organisation's coverage of the service in churches ranging from Belfast to Newcastle and Winchester.
In every venue, clergy will lead the local congregations in bidding prayers before the Westminster Abbey service begins and organists will help congregations with the full singing of the hymns.
Jews around the country will also be pouring into synagogues today to pay tribute to Diana in a way appropriate to their faith.
Chief Rabbi Dr Jonathan Sacks told Buckingham Palace that although he was unable to attend the funeral because Jewish law forbids mourning on the Sabbath, he had created a special service for Jews to observe which would express a "positive mood of thanksgiving" for the memory of Diana's life.
Dr Sacks said: "In a quite unprecedented gesture, Jews throughout the country and the Commonwealth will observe a special service of tribute which I have constructed for this unique occasion.
"Exactly as the service is taking place in Westminster Abbey, a Jewish equivalent service will take place in thousands of synagogues."
He said that his office had been overwhelmed by calls from British Jews asking how they could mark the occasion without contradicting their faith.
"There has been no precedent for it, and so as the nation grieves Jews in synagogues throughout the world will be expressing their grief in a positive mood of thanksgiving.
"What we are really doing is giving thanks for a life. We are paying tribute to a person who symbolises the sheer power of human spirit to turn its own pain into a power of recognising and healing the pain of others."
The vast majority of organisations and shops around the country will be marking the occasion by closing their doors for all or part of the day.
Some businesses are choosing to open up in the afternoon and then donate all their profits to one of Diana's favourite charities.
Even those who are forced to work today will be listening to the service on the radio and stopping at 11am to observe a minute's silence with the rest of the country.
Oil platforms and rigs throughout the North Sea will be honouring the silence, as will all the major British airports including Heathrow and Gatwick.
And motorists in Aberdeen will have no choice but to come to a respectful standstill because the council has arranged to hold all its traffic lights on red for the duration of the silence as a tribute to the Princess.Reuse content