I think that it's a total of two races of AM, AL or BL categories rather than two of each. Stolly, who knows his way around the Three Peaks, reckons you can add an hour on to your road marathon time for this race so 3-20 would give you around 4-20, which is well within the kind of time where cut-offs aren't an issue. I reckon a 4-00 to 4-20 marathon time would get you through the cut-offs more or less.