Newbie training

Hi people,

I'm a relative newbie to the running circuit, but would really
like to run the London Marathon next year. I was just wondering what training
schedule you would recommend over the next year? Is it a good idea to start
doing very long distances as soon as possible and then just keep at it, or is a
more incremental approach better (concentrating on longer distances for only a
shorter time)?

Also, I know there are a lot of entries for the marathon,
and not all get a place. Could anybody explain the selection
criteria?

Many thanks