I did it last year as part of a pair, we managed 8 laps but my team mate missed the cut off by about 20 seconds so only 7 counted :(
Great fun and the weather was amazing last year, the rooty downhill bits might get tricky if it rains.
Training plan was to ride my bike, twice a week for 10-15 miles. All off road and plenty climbs. Went to the gym a couple of times a week but nothing too strenuous.
Entered again this year so I don’t want to give too many secrets away ;)