After much help from TBB, here's my promised report on my first year with BT. I'm a non-techie light user, about 6GB per month download, and I'm 3km from the exchange.
Having been with Toucan/Tiscali/Pipex since dialup days, my service was cut off when TalkTalk took over Pipex and nobody could do anything about it for five weeks. Eventually I received compensation via Otelo. In desperation I called BT who said they could fix it and did so. Rates for my anytime calls/line rental/'up to 8MB' BB package were about the same as Pipex, about £27pm paying rental in advance.
There have been no line or phone problems. The broadband service began around 3MB, same as Pipex, but then speeded up. There seemed to be widespread slowdowns in late pm so I rang support and was told there were some issues. BT called again and offered an engineer's visit; a very friendly and helpful technician spent two hours checking everything and demonstrating his test gear, which showed no fault at home but possibly one on the exchange. After this the speeds increased.
There were widespread problems early this year caused by a fault on the Edinburgh exchange but service was maintained albeit slower. Since then I have enjoyed average 4.4MB with the range 2.6MB to 5.9MB.
I changed from XP to W7 last month and could not set up Thunderbird (no Outlook Express in W7) so I called BT support in India. BT does not support TB but Andrapuja said she would try. Turned out that TB's auto setup was choosing the wrong servers, plus other issues which she sorted for me.
To sum up, this month I'm pleased to sign up for another 12 months with BT (at a slight reduction in price) and I'm happy with service, tech support, and value for money.