Proberly no, like your father said your username and password are in the router - just like sky.
You could ask him to phone the ISP and try and get your logon info.
To find out the routers IP address. Connect to the internet and goto your network settings and look for your default gateway.
The default gateway is the router IP address
Alternatively, try and reset the router to factory default (there usualy is a pinhole reset button somewhere on router) and try to login with the default address (192.168.1.1), admin, Admin.