very simple.

there are only 2 types of internet routes

1. cable

2. through the telephone exchange which telephone line

now the only people which offer cable is virgin media i believe, the connection is usually very efficient as its not done through the old fashion telephone line, it runs through a fibre optic cable, usually small village areas struggle to get but go onto the website you can type in the post code and it will tell you, if you cant find ur post code call them as it may not be updated also if a few houses down use virgin you are in luck cause they can wire it through to your house,

you dont need a telephone line to be able to get broadband, they do packages like 2 for £20 or u can just pay £10 per month for 2 mb broadband.

secondly the telephone exchange, names such as

orange, t mobile, tiscali, talk talk, sky, toucan,etc they are all the same they all run through the telephone line by bt. so it doesnt matter who you go to it will still be a telephone line the internet you use,

its more expensive because you have to pay for bt line in order to get tv and broadband whereas for virgin you dont.

hope this helps