I've done the half, and tempted by the 30k this year (depending how fit I feel). As said, a map is in the pack, but I never needed to use it.
If in doubt, and you're more than half way, look for the big spire and run towards that.
Hills? just think of the views.
Note - this is a scenic, interesting and sociable friendly run, probably not one to plan and expect a pb or one for demonic competitive racing, as you run back through the tourists in the cathedral close, shoppers in the High St etc
(but then, I've never been at the front, so it may be more competitive there?)