I applied through my work and just found out today I've been successful. I don't even know why I applied...didn't think I had a hope in hell of getting in. I did the London one about 13 years ago in 5 hrs. Hated the training. I have done a few 10k's since then and took up running again last summer for fitness really (averaging about 5k in 30 mins) but have not been since October time as don't want to run in dark and cold and as I live semi rural also in the country lanes. I am in two minds weather to do this or give up the place. I work mon-wed shift work so fitting in training would be difficult then. But if I give up the place will I regret it and wish I would have just committed. I'm not a person who loves running and only really enjoyed it last year as it was warm and light when I went out. Not sure I will enjoy it so much now when I am out freezing and soaking wet in the dark.
Is it the London marathon? If there is someone else who really wants the place and you don't like running, I would say give it up. I think marathon training needs respect and commitment.
If you decide to do it, you do have enough time (just) but you will need to really commit to it.
Google marathon training plans and most of them will give you a three month option. But if you're going to hate the training (and let's face it most of it will be done in the winter months) is it really worth it? You've already done a marathon once so you know the pain involved! (5 hours is a good time though!)