Build up a good base of running fitness between now and October, then begin a 6 month training plan (loads available online). Just don't go all out just now and leave yourself burnt out by the time it comes along.
Figure out when in your day/week you can fit your running in and try those times to see if they work for you. As the last poster said, get your trainers and other kit early so you can get used to it. You don't want to run a marathon in kit that you haven't been training in!
If you plan on using energy gels then use these on your long runs so your body gets used to them.
Invest in a decent enough GPS watch and HRM, perhaps a Garmin Forerunner 110 or 15? Those are good enough for marathon training.
Find some nice enjoyable routes, ideally ones with extensions that you can use to add distance when needed.
Finally, figure out if you're a solo runner or a sociable runner! Some people I know hate long runs alone, but I MUCH prefer to run alone.