Did this event last year, yep practice your map reading. it is worth getting a couple recce runs in on the route, especially the latter stages when people are really spread out.
The hill mr immune is talking about is black cap, i live right near it so am up and down it a lot. Not as high as ditchlign beacon but after 50 miles its big enough 
A couple other points as it is your first ultra :
- Practice eating on the go and find out what works for you during long runs
- Train on trails where possible. I would say the route is 75% trail.
- Practice running with your kit (everything you expect to be wearing/carrying) on to get used to it and test it for any problems. You don't want to find a problem 20 miles into the race and still have another 30+ to go!
- Give yourself at least 2 days complete rest before hand and plenty of sleep the night before.
- During the race stay on top of your food and fluid intake. Little and often to keep yourself topped up. Once again, try the eating/drinking strategies before hand in your long run.
As i said, i live near the tail end of the route so any questions let me know or if you really want drop me a PM and can arrange to show you the last 15 or so miles pretty easily.
Hope that is some help to you.