Trick is to increase your training gradually, alot of injuries occur around February/March when runners increase the training too sharply. Your long run should increase by no more than 15 mins a week with a dip or two on odd weeks. Too many peeps go from nothing on 31 Dec to full on marathon training on 1st Jan. Work on your base training leading up to the new year. Get some milage in your legs.
Regular sports massages help with minor problems, ITB probs.
There are plenty of Lard arses that get round London, but they will suffer through lack of training and preparation.
It is far better to be prepared and run a comfortable if slower race.
I throughly recommend the Trailplus Marathon training weekends, I went on one earlier this year and it changed my who outlook on my training.