1. Don't up your weekly mileage that much, too much risk of injury, instead practise ultra pace on your long run and get this up to 15-20 miles, ultra pace means 2-3 mins/mile slower than marathon, I do 9:30 min miling as opposed to 7 min miling. I've done 6 ultras on mainly 20-30 miles a week
2. Try a run walk strategy say 9 mins running 1 min walking you can use the walk to refuel
3. Sort your refueling strategy and practise it, for a short ultra like this energy drink and /or gels is prob enough BUT also practise running slow enough that you can do 2 hrs or more on just water
4. Cultivate stubborness, look out for chances to develop this skill while training e.g plodding along in shit weather, rather than shortening your run or not going at all
5. Go run as much of the course as you can, although it's fun to have the challenge of navigating a unfamilar route don't do this on your first ultra.
6. Run off road as much as poss
7. Keep it fun, most ultras have a really nice vibe and everyone is really supportive