I think you should look at cable opti fiber its the way forward!
The issues I have with a BT line no matter how good your ADSL connection is all it takes is one more person down your road and you loose afew blips. 5 years ago it was fine todays high way traffic is too much for the old BT system to handle. Hopefully I will be getting over 30MB soon by friday actually O2 can suck on eggs!
As for sims Talk Talk sims are realy good £10 pay as you go can easily get you another £20 for free when you top up!
They gave me 60 mins free international calls which I use for international dialing of course!
What the regulators did to BT the other companies are experiencing now themselves