today i got my info pack from my chosen charity with my ballot application for the 2006 london marathon! having had a few cortisone shots recently and no transport plus not being able to lift bla bla bla i've shot upto 270ish. so marathon training is going to start somewhat casually lol. they sent me a training play but that starts in january so i have 5 months to get a really good fitness base up any suggestions on foods to avoid or eat?

That's so awesome that you're going to run a marathon! I'm thinking about running a 5K in November.
Anyway, to answer your question about what to eat. All the reading I've been doing have been stressing good carbs from whole grains (whole wheat, brown rice, etc.) to give you energy for running, lots of fresh fruits and veggies, moderate amounts of good fats (flax seed oil and nuts are mention alot) and lots of lean protein to rebuild muscle afterwards.
Obviously, you would want to avoid candy, cake and other sweets along with processed, fried and refined foods.
I'm no expert obviously but I'm sure someone with lots more experience will be around shortly to share their wisdom.
Good Luck!