What happened last year was that there were lots of signs and instructions clearly stating you would not be allowed into the starting pens until a certain time and asking people therefore not to gather there early. So we waited until they were meant to open, sauntered over......and found them already full of thousands of cyclists! So we'll ignore that this year and try and get in a bit earlier!
@Whorty you do have to wait in the pens for quite a while (even us last year when we arrived late/on time), but there were portaloos where you wait near the start - and further back than that lets just say a lot of the trees either side of the starting pens were being well watered while we waited