In reply to Mark Torrance: You won't like to hear this.. but that's what marathons and marathon training is like..
You learn. You learn in the training, you learn in the race. So that's why I wouldn't set your heart on no more. I'm down to 2:42 but have yet to run anything like a sensible race..
A mate for his first ran 1:14:35, 1:14:30 as his splits.. 2:29.. now he's running 80+ mile weeks, and a 1:10 half marathoner, former college funded athlete, but very very few will get a marathon so right off the bat..
I just think you are putting a lot of pressure on yourself to get this one right..
I've ran 3:03 (Snowdonia 08), 3:01 (Snowdonia 09), 2:57 (Snowdonia 10), 2:53 (Loch Ness 10), 2:51 (Snowdonia 11), 2:50 (Kiel 10), 2:46 (Dallas 09), 2:42 (Austin 12).
Only 2 of those have been adequate in terms of on the day performance, with Ok splits.. still a good 3-4 minutes off equals.
Loch Ness was a 1:22 and 1:31 split.. I should have been able to run a 2:48 at least in my sleep there... so the training is only part of the battle..