That's good, as I ask for an internal 56K modem to be installed on my new computer, I have an account with madasafish (pay as you go) and I want to keep my madasafish.com email address (which is my main one), so I've done well to have done that. I will get broadband with my other ISP, Plusnet, apparently they are giving you the option of a pay as you go account as a back-up.
Many people install a 56K modem as a backup when they first switch to a broadband connection, but you rapidly learn that in fact the broadband service is so reliable you never need the back-up. I have used broadband since it first launched in this country, and in all that time I have never once needed to dial-up.
If you do decide to install a 56K modem do not leave it connected to the phone line when it's not being used - if by chance you are infected with a dialer you could find yourself facing a huge phone bill for premium-rate calls you knew nothing about.