Old Age Pensions Information on the States of Guernsey website:

State Pension Information

https://www.gov.gg/oldagepension

What age can I claim my State Pension

https://www.gov.gg/pensionagecalculator

Paying additional State Pension contributions if taking early retirement

https://www.gov.gg/non-employedcontributions

UK Pension Centre, for those who have payed UK Pension contributions

https://www.gov.uk/international-pension-centre