I've no idea what ntl's off-net ADSL service itself is like, but would personally recommend against it, simply because calls to ntl Freedom tech support are via a premium rate number. I remember a thread here a short while back about someone who racked up quite a large phone bill from having to repeatedly phone ntl's expensive Freedom tech support line.
http://www.cableforum.co.uk/board/sh...hlight=freedom
Maybe have a look around at other ADSL providers...PlusNet, Zen, Nildram etc.