The ICO has implemented a version of this already on it's own website - a clunky box which won't go away unless the viewer accepts cookies.
Businesses have 12 months to update their websites - here is the text from the site:
put into practice over the coming months you are likely to start to
see more information about cookies on sites and be given more
choices about these cookies. This might include, for example, being
asked to agree to a cookie being used for a particular service,
such as remembering your preferences on a site.
Organisations will need to decide on the best way to provide clear information about cookies and to give people using their websites the right choices. They will also want to make sure that these changes do not adversely affect the experience of people using the internet.
A new website http://www.youronlinechoices.com/uk/ explains how behavioural advertising works and includes links to opt out options and policies for major advertisers including Google as well as an explanation of cookies.