Please download it from http://www.adobe.com/cfusion/tdrc/index.cfm?product=coldfusion&promoid=DJDUK use your Adobe ID and password to login and download CF11.
Let me know in case you face any issue while downloading it, if you get any error try another browser.
I can't download the trial of CF11. A browser window opens with just an Adobe logo and some parentheses, but no software downloads. I entered all of my information in the form.