I just finished something exactly like this using First Data Global Gateway (don't really want to provide a link, can find with Google). There's no Python API because their interface is nothing but http POST.
You have the choice of gathering credit card info yourself before posting the form to their server, as long as the connection is SSL and the referring URL is known to them (meaning it's your form but you can't store or process the data first).
In the FDGG gateway "terminal interface" you configure your URL endpoints for authorization accepted/failed and it will POST transaction information.
I can't say it was fun and their "test" mode was buggy but it works. Sorry, don't know if it's available in UK/EU but it's misnamed if it isn't :)
