Unlike in France, they cannot force there way into your home, only police with a warrant can do that, i believe.This is it. They can only do you if they catch you in the act. Since the latest update, you can have a reply, just so long as you don't use it for watching live broadcast or iPlayer.
Last i heard. They aren't police officers so they can't arrest you or use PACE, so can't interview under caution.