when i considered my broadband, when i recently moved house, i'm similar to the OP, although my work doesnt rely on it, i'm not really bothered by outright speed, its how reliable the service is.
cant get Virgin cable (used to have that - very little issues), so i have to use ADSL.
I think they are 2 companies that use LLU in my area, but i was reluctant due to the companies involved, AOL and TALKTALK - if i remember correctly.
I looked for a small ISP without a long contract, as the way i see it, if you have a problem, with a short contract if they dont solve it quickly, you'll just go somewhere else... if your tied into a 12 month contract, there is nothing much you can do, so they can take ages to sort it out.
I looked at a few ISPs and went with AAISP
http://aaisp.net.uk/
They have on peak and off peak tarrifs, which most do these days but peak runs from 9-6 monday to friday, which suits me, cos i'm at work then anyway, other isps choose much higher peak times, and some include weekends as peak! - With AAISP its a modular system, and you buy peak and off peak units.
Its not cheap, but so far (4-5 months) its been absoultely flawless service.
they are really helpful too...
When BT connected my phone, they made a mess of it (no suprise there) and left a tag on the line for broadband. This meant that i couldnt sign up for a broadband service without a migration code, which of course i didnt have, cos i didnt have broadband, it was a brand new contract on that line in my name!
after 2 telephone conversations with BT lasting over an hour in total, i had got nowhere... they couldnt help me, and told me as much on the phone.
Phoned AAISP, got put straight through to someone who knew what they were talking about, said i wanted to join them, explained my problem, they contacted BT for me, and sorted it all out!! - result!! If i had to call BT again, i would have lost the will to live i reckon!!
No contract, i just have to give them 30 days notice, then i can leave.
no drop outs, no throttling, no problems with torrents (TV shows etc).
got a free modem (which is rubbish, doesnt like torrents and web at the same time) but is useful as a spare as my netgear has just died.
I couldnt be happier with them, if that changes, i'll just move onto another small isp, there are lots of them.
Ive found with these things, the bigger the company, the more difficult it is to sort things out if/when somthing goes wrong!
sorry for the long post.
hope this helps