NO ! You either want to save money or you don't. If you're getting rid of it, you could donate it to this site by PayPal - contact Daniel (
admin).
What you do is to sign up for a BT PAYG account then you can use the dial-up number for them, and save yourself a shedload if as you say, you don't use it too much. Don't forget, with certain Telco's, you have to put the international code, +44 (drop the zero) & the rest of the dial-up. They have
ISP Lookup
lists and will automatically charge you at the 0845 rate otherwise. There are a couple of others in the list if you're not keen on BT.
You should be able to pick up your mail on the Wanadoo account by using webmail or whatever.