Blueyonder and Linux - help sought

OK, so I have not one but two shiny Linux-running laptops. And I am in a house with Blueyonder broadband. (Also four cats, but that's not important right now.)

Blueyonder say: "It is possible to configure Linux to work with Telewest broadband, however our installers will not connect to a PC running Linux, and unfortunately we are unable to offer any technical support to users choosing to run this operating syste, so there"

Appreciating that my only previous experience of setting up broadband consists of plugging in a router, and plugging in a blue BT modem thing, how should I proceed? 'you should put your laptops away, stay offline and spare us your infernal ignorance' is a reasonable answer, but I'm kind of hoping for something more ... progressive.