I signed up for a Chargify account a couple days ago, been working on integrating it into my app. Really simple, great API. I haven't run any transactions through it, but on the integration side, it's pretty solid.
As far as I can tell, you can only use Chargify in the UK if you have an account with Barclays. And, on top, you still need to get hold of costly payment gateways and merchant accounts...
About other countries and currencies: http://support.chargify.com/faqs/general-questions/does-char...