Squide00
When you enter, I think you'll have to put your best time/predicted time, and when you get your number, it should tell you what starting pen you are in, based on that.
The idea is that the quicker runners will be in a pen towards the front, and each pen behind should be runners who are possibly slower than the pen in front, and so on, so you should be running with participants of a similar standard.
The run is quite busy on the first half, as it has the half marathon runners in as well, but in the second half there is plenty of room.
My wife is doing the full, and its her first too, and I think its good course for a first one as the 2nd half is also pretty flat, (apart from a cheeky incline at 23m !!) the scenery from mile 18 ain't bad and you can focus on the sea/sights, and at about mile 24 you can see the cathedral in the distance, and this picks you up as you know the finish is in sight.