Ok so you have looked at all the options and you think ADSL is the way to go.
At this point you need to consider who provides your phone line. If you have a BT line this gives you the widest choice of broadband and phone services. This is important as YOU can mix and match the deal that suits you best.
Basic broadband 1 or 2 meg services start from £9.99 per month. These are offered to ALL EXCHANGES that have broadband: There is no need for a provider to have equipment in the exchange, known as local loop unbundling. These services are provided by BT, and other companies that buy broadband from BT Wholesale and sell it to you, often cheaper than BT.
Some exchanges have equipment from other providers; this allows providers to offer services that go beyond the BT offerings. These offerings fall into 2 categories:
1) Bundled offers (Phone, ADSL)
2) ADSL only.
If you only need one incoming line and have basic internet needs then the carphone warehouse offer is good as for £21 pounds a month you get free national and international calls and 8meg broadband, you do not need to pay BT £11 a month for line rental as line rental is paid to carphone warehouse.