First I've heard there's any geographical limitation on screaming.net, within the UK. There might be difficulties picking up the relevant CDRom from Tempo if there's no Tempo where you are, but that's what smail mail is for.

As for the adverts on screeen, that surely only applies if you actually go to the home page of the Internet Service Provider when you open your browser - the only time I do that is when I want to complain about something going wrong. Otherwise set the browser to use your own home page as an opening screeen -- or Mudcat. Or the Hunger Site