In Devon and Cornwall, the eclipse will start at about 18:18 BST, peak at 19:15 and finish at about 20:10.
In Guernsey and Jersey, those timings will be about 18:21, 19:17 and 20:10.
The Cosmos Community Observatory on the Isles of Scilly is hosting a free event between 18:00 and 20:00 on the lawns of the Karma Hotel on St Martin's.
People would be able to view the partial eclipse through telescopes with solar filters and eclipse glasses at the event on Scilly, which is only open to those who live or are holidaying on St Martin's.
Payne said: "It's a really big deal. These kind of eclipses don't happen very often and one almost this deep, almost near to totality is pretty rare".
In Cornwall, Kernow Astronomers have stocked with 420 eclipse glasses to give out at their event at the National Trust car park at Carnewas, at the Bedruthan Steps near Newquay, on the county's north coast.
Frank Johns, of the club, said: "We really have got a good view to the west and you can see right towards the ocean."
The Smugglers Rest is Talland Bay, near Looe, is holding a paid ticket event.
Bosses said they planned to use proceeds to help pay for an access ramp at the venue on Cornwall's south coast.
Like the other paid-for eclipse events, organisers have advised checking for ticket availability before travelling.
In Guernsey, Dr Jean Dean, from La Société Guernesiaise's astronomy section, advised people to head to the west coast of the Channel Island to enjoy the spectacle.
She said people needed to use eclipse glasses or have their back to the sun and project it onto a piece of card.
Eclipse glasses have been given out are Les Bourgs Hospice charity shops in St Martins and St Sampsons.
Dean warned that if anyone looked directly at the sun they would "burn your retina in your eye and you will be permanently blind".
She stressed people should not use the eclipse glasses with other optical equipment such as binoculars, but could put them over spectacles.
Jersey Astronomy Club said it was setting up several solar telescopes by the slip at Le Braye on St Ouens Bay and it planned to have a supply of solar glasses for people to wear.
The club warned people not to attempt to look through binoculars or telescopes which did not have proper solar filters as they could collect more light than the human eye could cope with, risking blindness.
It said, without proper solar filters, "the only safe way to observe an eclipse is to use the telescope or binoculars to project an image, not into your eye but onto a piece of white paper or card", and removing or taping over the front of the finder scope "to prevent any accidents".
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