2) ....apart from "the worst ADSL ISP", BT are lightyears ahead of TalkTalk/Tiscali.
Well, we could debate LLU and how LLU is preferable to anything transiting over BT's network. However, given the original poster is out in the sticks, it's somewhat irrelevant.
The problem with BT is that digital circuits (Megastream etc.) are a nice little earner for them. So it could be said that it's not particularly in their interests to develop competitive products at a lower price point (or at least the imposition of technical/commercial limitations).
The other problem with BT is the size and complexity of their organisation.
I'm a little dubious of TalkTalk, they do have their place (just as BT have theirs), but there are better LLU providers out there.