If you've never used safety equipment, Check your area for a climbing equipment store and pay them a visit. Tell them what you need the equipment for and they should be able to assist you. A standard body harness is adequate however, You need to know how to properly attach your lines to the harness and how to do a self rescue in the event you have a fall.
Approx. 18 years ago, I was working on a 2 story house here in Maryland which has a fairly steep pitch and everything was going as usual and suddenly, I slammed against the roof. After trying to figure out what had just happened, I looked up to the peak and realized the only thing which saved me was my 1/2" life line. The ironic part is, I had just started using the equipment 3 months earlier. I was 2-1/2 stories off the ground at the point where I slipped. I most likely wouldn't have survived the fall and the life line did its job. I ended up approx. 3' below the area I slipped So keep in mind, When you start using the equipment, Make sure your line will "NOT" allow you to get any closer than 6' from the edge.
Yes, It's a pain in the ass with the extra set-up and tear down time but I look at it this way, I still have an ass to have a pain in......
Also, When you purchase the safety equipment, Purchase a "ROPE" protector. They are simply a canvass sleeve which you will need to adjust as you move back and forth from side to side however, The rope protector prevents the roof ridge from cutting and fraying your rope.
I purchased all of my equipment from JRacenstein out of New York. They sell window cleaning equipment and offer fall protection equip. I'm sure someone else here on the forum can provide other resources as well.
Mike