Experts are divided on eye safety
The UK eclipse website and various scientific bodies say it can be viewed with the naked eye only for a few minutes when the sun is totally obscured.
However, eye specialists say the sun should not be viewed directly at any stage, a stance backed this week by the chief medical officer Liam Donaldson. Only people in the Scilly Isles, most of Cornwall, south Devon and Alderney will experience the effect of the moon covering the sun entirely.
The Association for Science Education says in its safety code, which was sent to schools, that it will be "safe to view the totally eclipsed sun directly without any filter and admire the faint and beautiful corona".
NASA backs this advice, as does the Central Laboratory of the Research Councils. However, all say viewing should stop as soon as the total eclipse ends.
The Central Laboratory warns: "As soon as the first light of the sun has reappeared, producing a spectacular 'diamond ring', you must look away immediately and use the special filters once more."
However, Fight for Sight, a charity aimed at preventing blindness, says that many people will not be able to judge when it is safe to view the eclipse.
"It's our advice not to look even during totality," said Rebecca Mullen of the charity's eclipse information service. "We want people to have lasting memories, not lasting damage," she said.
Fight for Sight says cardboard pinhole cameras - where the image of the sun is projected on to a small screen - are the safest way of viewing the eclipse.