If you do the first thing you should do is turn off "Smart Set Up" on the Homehub as it can cause problems with tablets and phones.
As well as what gg30340 has said, if you use your BT email then here's how to set it up on your iPad - http://bt.custhelp.com/app/answers/detail/a_id/46673/c/346,6588,6591#apple.
Though you can also use the webmail platform via https://signin1.bt.com/login/emailloginform
If you need the IMAP or POP3 settings they are here: http://bt.custhelp.com/app/answers/detail/a_id/44917/c/346
I think that's all the basics you need to get started when your new Infinity connection is installed.
If there is anything else just pop back