There are two options to call the 1K line from the UK:
1. Call the regular US 800 number using a US mobile, UK mobile or UK landline. I have used this number well over 100 times from the UK, it costs the same as a regular US call. When you dial you are 'warned' that it will be charged as a regular call to the US.
2. Call the regular US 800 number using Skype
3. Call one of the AT&T access numbers here:
http://www.att.com/media/att/2012/su...ccessCodes.pdf
chinatraderjmr- not sure where you're getting the comment "That costs too much for the new UA" from - using AT&T for international access costs UA significantly more than having a dedicated set of UK numbers for themselves. They're not saving money by doing this. Using AT&T gives a freephone number in the UK that people can call and allows the regular 1K line to be accessed from any of the countries linked above.
And FYI if you are calling from a UK mobile, calling a UK landline number (or freephone number) costs significantly more than calling the US. (approx. 15-25p / min vs. <5p / min)