I have no idea whether or not this can be done.
Certainly there would be an issues sending any email via ntl, as you have to be online direct to their smtp server. Unless you can dial into ntl i.e. a standard ntl dial up number normally used by landline based modems will accept your mobiles connection, you can't send that way.
If the setup of the phone is anything like setup of other PCs say using Outlook Express, with such other PCs conected via the internet to ISPs other than ntl, you should be able to receive email from the ntl server. You'd need to get the syntax of your user account password and POP servers correct. AS far as I can tell the user name is everything before the @ntlworld bit of the address, passwords are of course case sensitive, and the incoming mail server is pop.ntlworld.com, port 110. I don't beleive there are any other secuirity settings needed, if outlook express settings are anything to go by.
You might need to look at the size of emails being sent to you though - your pay as you go bill would become enormous