You do need a phone line before you can go any further. The phone line then needs to be activated. The price quoted may therefore be correct as it includes installing the line and not just activating it. It's a crime what they charge.
Assuming you would like broadband, you would need an account set up. BT are doing some cheap packages at the moment and I find them to be very reliable. There is a monthly charge. Have a look at the link below to see the packages available.
http://www.productsandservices.bt.com/consumer Products/displayCategory.do?categoryId=CON-TOT AL-BB-R1&s_cid=con_FURL_broadband
You will need a broadband router. You may get one free with your broadband package, this is usually the case.
Your laptop must have a wireless card or a wireless adapter to make a connection.
Once you have done all of the above, let us know here and we will guide you through setting up a wireless connection with your laptop.