Customize an order confirmation page with a link

Hi there,

I've added service products to a site. Once the service has been paid for, a standard SS confirmation page presents.

What I need is content on this confirmation page, including a link to an external website, as part of an additional step for users.

I have wondered about using css generated content that includes hyperlinks to enable what I need. Has anyone ever achieved this before? 

Alternatively, perhaps it's possible to incorporate script to the site to enable linking to a different, customized confirmation page once a payment for the service has been made?

Any insight about the possibility of doing this will be very appreciated. 

Many thanks!

Angela