Not a dim question, myself like many others is in the same boat as you, your best bet is simply to sign up. I did last week but as the service doesn't come live until 1st August, i probably won't hear anything for a few weeks.
I had the same question in another thread, the (predictable) answer is that nobody really knows, but yes, as the previous poster says, best to sign up.
I signed up using the online system, and I've already got a confirmation email for the order, saying I'll get BT Sport 1 & 2 and ESPN from the 1st August, with HD for a year etc. Mind you I already have the BT Sport SD and HD channels on the Vision box, they are showing video previews all day long and they work just fine. I'm guessing all BT have to do on the 1st August is simply turn them off for people who haven't signed up.
One of the purposes of BT Sport is to retain customers. So to get the channels you must renew for at least 12 months (and sign up for auto renewal).
You have a straight choice - commit to BT and get the new channels, or leave yourself free for your current contract to expire, but don't get the channels. This is how BT intend it to work.
I thought Ofcom had effectively outlawed auto renewal contracts.
As of 31 December 2011, rollover contracts will be banned, Ofcom confirmed
BT, AdEPT Telecom, Axis Telecom, eZe Talk, italk telecom, TalkTalk Business, Titan Telecom, Optimum Calls and others have been ordered to completely remove ARCs from the market by 31 December 2012.