Hi the main thing you need is a Service Provider that offers LLU forget the Bt Rebranded products as all seem to have problems and as Isitme say`s O2User . I have not heard anything but good news from O2/Be LLU There is quite a few O2 Customers on Skyuser also Skyuser sister site - O2user. Anyone can complain about what they have heard. But it is about needs and everyone seems to have different needs. This might be helpful a list of ISPs
Hope you get sorted