It wouldn't be overly difficult for ntl to provide
http://username.ntlworld.com or
http://username.ntlhome.com but this would encourage unwanted traffic on the network.
As for your questionaire, I have voted no. If you are prepared to pay a small fee to ntl for a domain name, why not pay the small fee to purchase the domain name you want?
Failing that, go for one of the many free forwarding services.