The license fee is a fee for a license to receive a broadcast TV signal. That covers all channels. You cant simply not watch BBC and refuse to buy a license.
I actually thought it was a licenece fee for "owning tv equipment".
IE if you ONLY have monitors in your house (to watch dvd's etc on) then you would be fine - but they make it nigh on impossible to get away without a licence if you have any kind of actual tv reception equipment in your house (even if it isnt attached to an aerial)