It's on this page: http://search2.hmrc.gov.uk/kb5/hmrc/forms/view.page?record=tR6ypm32iVs. It you get the message
"If this message is not eventually replaced by the proper contents of the document, your PDF
viewer may not be able to display this type of document. "
then your browser isn't using Adobe Reader.
Just download the file (e.g. right click, choose Save Target As or whatever is normal for your browser), save to your desktop, open from there.