Hiddles!

I have just randomly accepted a friend's offer of a 2nd row ticket to Tom Hiddleston's premier of High Rise - Meep! I've never been to a movie premier before and am now panicking about what to wear. Plus I'd just booked my train tickets to go see my Mum the day before this premier so now have to travel up to hers, then the next day travel down to London, and stay overnight... Um, what am I doing!? Just to see the back of Hiddleston's head...

Does anyone know how these shenanigans work? Do the plebs with tickets have to arrive earlier and walk the red carpet? Are we allowed to take cameras and hang around like paparazzi? Can I wear my Keens?