After a bit more fiddling, and looking up other support forum posts, I've put together the following:
CultureInfo info =
Thread.CurrentThread.CurrentUICulture = info;
] = info;
, info.TwoLetterISOLanguageName, appPath));
This does redirect to the new language setting for the swapping of languages, but the moment a link is clicked from any of the sitefinity generated links like menus, etc. the site redirects to the next page in the default English language, not the currently selected language.
Could you give me some example code on how to swap the language around programmatically?