Hi Fiona
I'm sorry, we're not able to tell you why you can't access them. I would normally advise someone to log out, clear their browsing history and then try again. If that doesn't work then send an email to tech@benefitsandwork.co.uk and hopefully they will be able to say whether it is something their end or your end.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems