Richard I am at a similar level to you time wise and have not used a map for a few years. I did the Chew Valley Skyline (BL) in March which I clocked at 14m but I didn't look at the map once as the day was so clear I could always see runners ahead even though there were just a few more than 100. Holme Moss is further than I've run to date, I've never run an 'A' race before either but posted my entry today.

With a reccy, a few long runs between now & then and sensible map use I'm sure we'll be fine. Go for it mate!