Mick, it's 2.25.00 at 11.84 miles and if you've not covered this distance you're not carrying on and you'll be directed to the half marathon finish line. I know folk who have missed the cut off.
It's fine for a first marathon. Well organised, there IS a bit of a hill that saps your will to live at mile 18 when you climb it for the second time (the course is a two lapper) but I enjoyed it.
Didn't mind the greenway.