The private island, tenanted by Sir Peter Ogden for the past 25 years, will open up to 250 ticket holders on 29 July.
Tickets for the event go on sale today via ticket platform www.ticketsource.co.uk, priced at £40 for an adult and £20 for a child aged 7-16.
There is a maximum of six tickets per booking but there are five special tickets for groups of 10.
Included in the ticket price is return travel on Herm Trident, time to walk around the island, and a baguette lunch served in the manor garden.
Refreshments will be available, with a Pimm’s bar and the opportunity to try a free Liberation ale in Jethou’s pub.
There is also an opportunity to win four tickets as part of a raffle draw that will take place on 30 June.
Raffle tickets cost £2 each and can be purchased from the Les Bourgs Hospice charity shop or the Health Connections shop in Market Square.
Les Bourgs fundraising administrator Liz Stonebridge said that the hospice was grateful to Mr Ogden and the team in Jethou for their support.
‘In the past we have held events on Jethou via our “Friends of Les Bourgs” fundraising arm, and the team over there always go above and beyond for us.’
The charity day will also offer people the chance to buy tickets for a separate raffle, with a top prize of a 25-minute helicopter ride.
‘A number of local companies have kindly donated prizes for the raffle. It will be another opportunity to support the hospice and help us reach the £1.6m. it costs for our overheads,’ Miss Stonebridge said.
She added that past events had sold out, and she expected this event to do the same.
n Pets are not allowed on the island and smoking is prohibited. The trip is not suitable for children under seven or those with mobility issues.