If you want an unlimited and uncapped product why not look at one of the LLU providers,Check to see if Be* is available at your exchange.
http://www.samknows.com/broadband/phoneno.php
The only thing that may go against a Max adsl or Be*s adsl2+ product e.g. is the legnth of your telephone line, which could cuase a problem if you have a long line, and certainly if you are over 5 Km from your exchange Be* would not provision you.
The reason I went with Be* they are the only LLU provider that have a three month NO STRINGS notice period, and your telephone remains with BT so you can use the cheap providers such as 18866 etc for your calls. See the link below
http://www.theregister.co.uk/2006/06/01/be_unlimted_24meg_review/
Also for further information
http://www.beforum.co.uk/forum/default.aspx
Most migrations occur withing 8 days ... new provides can be as fast as 4 working days.
Things can go wrong of course. This is usually down to third party suppliers, although Be* never blame them- BT screw up a small percentage of the migrations, and LLU to LLU is still a cease and re-provide. The Be Box can be late arriving in a small number of cases, thanks to our friends at parcelforce.
I am very happy with my Be* connection, and have not had any big problems with Be*
support is OK and improving,[i.e. 0800 numbers in july] and Be* have promissed investment in extra bandwidth as the network grows to keep contention invisible