I don't think it is supposed to be for all routes, just the ones mentioned on the website.
I was able to see LHR-JFK availability at £100 + 30000A
But unlike normal long haul, if I add a domestic it's not free.
MAN-JFK is £100 + 40000A
Given I can get it for a lot less than £500 by paying cash I don't think I'll bother.