In reply to Zen:
A hill rope is usually around 30m, about 8mm diameter roughly, and dynamic. However, if you ended up on a proper climb, then you want a proper climbing rope really.
Generally a hill rope is not designed to take a leader fall. If I carry one, I generally just take a large sling and a screw gate to use with it. I would use it in a circumstance where I was happy going up a section without protection but someone else with me might need the assistance of a rope for confidence more than anything.
If you are wanting to place gear then you should have a climbing rope and a harness. You can get any length of rope you like, they are easy enough to order by the meter, so you could take a short rope if you felt that was all you needed.
If you are looking at hill rope work, I would recommend either going out with an experienced friend or getting on a course.