Maybe you need to broaden your definition of what constitutes psychology work experience. For example I have just looked at some volunteer web sites for opportunities in my local area and I found the following:
A school wants someone to go in and listen to children read. Well, psychology covers child psychology and educational psychology. Plus it will help your teaching and observation skills which are both useful.
Various organisations wanting people to befriend/mentor the elderly, the disabled and young people who have problems. This may not be an area of psychology that particularly interests you, but many psychology graduates will go into these sort of fields so it's good experience.
Various organisations wanting people to train as advisors.
I think all these would look good on an application form. You just need to make it sound good! I think they ask for work experience just so they can see that someone is geniunely interested in psychology. They just want to weed out the students who just randomly seem to pick a subject or want to study psychology 'cause they once saw an episode of Cracker!
Some useful volunteering websites are:
http://www.do-it.org.uk/
http://www.csv.org.uk/Volunteer/
http://www.volunteering.org.uk/
http://www.timebank.org.uk/