Section 4(b) of the Public Bodies (Admission to Meetings) Act 1960 requires that agendas must be published on a website
Section 19(1) of the Freedom of Information Act 2000 requires that the council publishes a Publication Scheme and published information according to that scheme. Minutes and agendas should be part of the scheme. Technically they do not have to publish to a website, but this is highly recommended if they have a website. If they are not publishing to a website the Publication Scheme should tell you how you can get hold of the information. The ICO would be port-of-call if they are not complying with this law.