Microsoft has just confirmed in a short post on its community forums below that Windows 8.1 Preview is now available in the English (UK) language from the Store and ISO file download.
Source: Windows 8.1 Preview available in English (United Kingdom) - Microsoft Community
See also: http://www.eightforums.com/tutorials/27188-windows-8-1-preview-download-install.html
We’re pleased to announce that we have expanded the supported languages for Windows 8.1 Preview to include English (United Kingdom), or EN-GB. If the base language of your PC is English (United Kingdom), you can now download Windows 8.1 Preview from Windows Store.
Source: Windows 8.1 Preview available in English (United Kingdom) - Microsoft Community
See also: http://www.eightforums.com/tutorials/27188-windows-8-1-preview-download-install.html