I am in the VLM (bit of a suprise as I got a club place) and have been training well untill about 4 weeks ago.
I did the Cambridge Boundry Marathon in March as a training run then went on holiday (only managed time to get one run whilst away) Ever since I have been plagued by colds and coughs and my plan has gone out the window.
A freind of mine who trains and compeats in Europein equive events said that I should not run for the next 2 weeks as it won't affect my fitness (that was after they said if a horse sounded like me after tonights short run the kindest thing to do would be to shoot it).
Deep down I know there is a point there, but cant help think I need to keep some movement of the old limbs in the next two week.
I was once told its about a mile per day to recover, however for me who's fat and forty is it takes a bit longer. So it boils down to which race you want to do better in. Personaly I would treat the HM as a training run at Marathon pace (or slightty less)
Thats my opinion, and probably not what you should do, but enjoy it what ever you decide