Really? Advance booking is almost never necessary outside of massively popular films, which only tend to happen once or twice a year - The Avengers and Skyfall for this year, possibly Twilight too. The convenience is nice, but what's five minutes in a queue, really?
I just got my Premium card, out of the blue - no email or anything - and I'm absolutely delighted. No more 3D "uplift", 25% off food and drink... My birthday's tomorrow, so Cineworld timed this to perfection!