You're not going to find 8Mb ADSL that really has no download limit for £15 a month. The Pipex one for example has a 2GB limit at that price.

Even the services that claim no limits have them when you read a little more of the small print. Plusnet for example talks about "No fixed download limits" on their £15 Plus product, in reality once you hit 4GB peak traffic they start reducing your download speed. Plusnet (and I few other providers at this price point) are also great at changing the rules every six months, often without telling the customers

As I heavy uploader/downloader I have been caught out far too often by the goal post moving. I now stick to an ISP that is completely transparent about their limits, but charge a sensible price (i.e. it is not as low as £15 a month).