Hello canyourepeathtatplz and welcome,
Hmmm. Difficult question as you haven't provided enought details about your setup for anyone to answer properly.
It depends on whether you are using BT Broadband or BT Infinity as to whether you can eliminate the Homehub.
If you are using BT Infinity, you can replace the HomeHub3 (HH)3 but not the Openreach modem - see here for details:
http://community.bt.com/t5/forums/searchpage/tab/message?q=airport#message-list
If you are using BT Broadband, you can use the Airport Extreme for wireless if that's what you wish. The Airport Extreme has no ADSL modem, so it can't do the connection to the telephone exchange, so you will still need the Homehub (or any 3rd party ADSL Modem router) to make the connection.
If you wish to use the Airport Extreme for wireless I would disable the wireless from the Homehub first though using the Advanced settings->Wireless at http://192.168.1.254. Plug the Airport Extreme WAN port into the HH using an ethernet cable and use the Apple Airport utility.
Hope this helps!
