This can be done through your student portal (on the Welcome Tab).  On that page you will see messages in the in-tray, one of which will be from Stephen Holdcroft, Head of Recruitment.  On the right hand side of this email (under Action) you will see the option to click on ‘view offer and respond’.  Click on this, scroll down and you will see the option to ‘accept’ or ‘decline’ the offer (in pink).