Hensler's High Aven is a 33m pitch requiring a minimum of a 40m rope for traditional SRT. The next longest pitch is Haigh's Bottom Pitch, which is 13m long.
So, I'd take a 20m and 15m ropes for the pitches as far as Hensler's High Aven and two 40m ropes for Hensler's High Aven. That should give you plenty of options should a rope get stuck, and allow you to avoid long ropes on short pitches.