Good to see that the HSE are now promoting the sensible approach to electrical safety testing that SSS have always advocated. If you have situations such as offices, it is not necessary to have equipment tested annually.
Their publication "Maintaining portable electric equipment in low-risk environments" is short and readable. You can read it at http://tinyurl.com/bizinf-2y219.
And their web page "Portable applicance testing - frequently asked questions" is also worth looking at.