You need an embassy visa for Guernsey if you have an Indian passport

Travellers need a visa to visit Guernsey for Business or Tourism. Travellers must obtain this visa from a local embassy, consulate, or visa center before travelling. Guernsey is moving from physical immigration documents to eVisas. If you use a biometric residence permit (BRP), biometric residence card (BRC), or visa vignette sticker or ink stamp in your passport to prove your rights, or to enter Guernsey, check the link to find out what you need to do. Creating a Guernsey Visas and Immigration (UKVI) account to access your eVisa is free, straightforward, and the move to an eVisa will not affect your underlying immigration status. Visa nationals should continue to carry their in-date physical immigration documents with them when they travel internationally, along with their passport. If you have a biometric residence permit or card (BRP/BRC) you should continue to carry it with you when you travel. If you use an eVisa to prove your rights in Guernsey, then you must tell the Home Office about any passport you intend to use for travel if it is not already linked to your UKVI account. Access your UKVI account by checking the link to do this well before you travel.