Torn fibres in Achilles early in 16 week London Marathon training schedule

Hi all,

About to take on my second full marathon and was doing the Intermediate 16 week training schedule on this website.  Three weeks of the schedule down and the half marathon was the long run.  I did it in zero degrees and it went fine and I got 1:58 on what was an "easy" run and felt just fine.  So all good.

However, I'm unsure of how it happened but I tore a few fibres around my achilles.  Went to a physio and he said I'd need a few weeks off and rest it, do some stretches and put ice on it/raise it as much as I can.  A week later and he said it would likely be a further ten-fourteen days.  I've been following his advice (doing some stretches on a step, then stretching).  When I get up in the morning everything is fine for an hour, and then after some walking, stretching the ankle feels like running your fingers up and down a comb.  It's not painful, just an odd feeling.  I also don't know whether to do the stretching when it feels like this either. 

Now given that at the end of this week I will have ten full weeks left until the Marathon, I am basically waiting on the physio appointment tomorrow to see what I can do... I have made my peace with not getting a good time with these three weeks out, but I don't think I could face just not doing it (if that's what it comes to) after waiting for the London Marathon for five years and running for charity. 

Whilst I understand that the physio willbe the best advice no doubt, I would appreciate your two cents on my situation from a very determined runner.

Thanks