#2 Apr 10, 2014 03:30
You didn't tell us which version are you currently using, but the process is basically the same. Enable the new locale and reset all the places where it is applicable.
Thus, go to the Locales tab (http://b2evolution.net/man/locales-tab), check the enabled box for en-GB and click Save !. After that, it's just a matter of change each collection's locale (http://b2evolution.net/man/blogs-general-parameters) and the user's too (http://b2evolution.net/man/user-preferences).