Ok now I work at carphone warehouse so I do this every day, I can do a search for you if you if you e-mail me with your post code and home phone number to
elliottdalton@yahoo.co.uk
Ur best bet would be AOL flexi, it's just Internet but it's only a 30day rolling contract so you can cancell it when ever you want. Now depending on who's in ur exchange depends on how much it is, the most expensive on that would be 9.99 for the first 3 months and then 19.98 there after.
You do need a BT line tho.
For o2 you still needs BT line and if you have an O2 contract it's 7.50.
Orange is better, as if you have an orange contract then your home broadband is free!!!
All this information and prices depends on where you live and who controls your Internet exchange
But for more info email me and I'll get back to you as I get my e-mail at work
Thanks
Elliott