Pain in the ass

Although I now have a genuine doctors certificate, I think the hamstring is going to prevent me from doing a single long run before the Beauj. Do I:

a) Ignore the training implications and hope to get round by the skin of my teeth.
b) Drop down to the half or even the 12km

I have found a suitable method of removing the pain, a couple of paracetamol followed by a few beers. (It is not a bad pull, it just results in a pain in the butt :) )