I have the same problem! For me numbness starts after 15/20 mins on my middle toe, before speading to my smaller toes, down the side of my foot and along to my heel. At its worst point, the whole of my foot would be completely numb, with stabbing pains in my middle toe. But bizarrely, after around 90 minutes, the pain goes away (or maybe the other parts of my body hurt so much I don't notice any more!). I'm a mid-foot striker, and have experimented with changing my foot strike to see if it helps. I can't say that I noticed much difference.
I've now tried five completely different types of shoes of varying support/width/size along with tying them differently, and the problem remains. That said, it is better now that I have insoles and neutral shoes than when I used a stability shoe. I also realised that I clench my toes when I run, so I've been working very hard at relaxing my toes and that seems to help. That said, I'm not sure that will be the case after a 20 mile training run! Glad to know I'm not the only one, because up until now people have looked at me bizarrely when I mentioned it.
Thanks all. Yes, I'm torn between losing more weight before I seriously start my programme, or trying to train and lose weight at the same. I've only got about 2 stone to lose now, so that's better than 4 but the hardest thing is keeping the weight off! For the half marathon I really struggled with hunger and keeping my weight stable, but I think I was probably not eating enough. So, lesson learned and I'll be much smarter for the half marathon.
The main I think will be getting all the miles under my belt - that really helped psychologically and physically for the half, and I know that the marathon will an entirely different beast. I feel like there's so much I just don't know about how to prepare and it's both thrilling and terrifying!
Thanks for your suggestions everyone! I didn't get picked for Berlin so I've bitten the bullet and entered Edinburgh marathon. I feel sick even thinking about what lies ahead, let alone making it through to the start line in one piece. Now to find a training plan...
Thanks for the suggestions. I can't do any weight bearing activity like kettle ball work (which I was previously doing), but yoga is a great suggestion so I will check it out. As for races, it seems like Loch Ness, Dublin and Newcastle are front runners for now!