Posted: 29/12/2014 at 21:20
There is a thread entitled "wannabe ultra runner", which is a veritable treasure trove of information for a person attempting an ultra for the first time.
Here is a link to one of the more popular 100k training plans, which would provide a reasonable starting point.
In terms of pacing strategy, your best option will probably be to walk all the uphill sections from the opening gate, while running the flat and downhill sections. When the organisers publish a course profile, I will be able to recommend a more detailed strategy.
You have until October to prepare, so your marathon training plan is a reasonable starting point. The main change would be to introduce back to back long runs. For example while your long run might have been 18-20 miles for the marathon, you would do something like 20-25 miles on the Saturday, then do 15 on the Sunday while your legs were still tired.