For the really low pitch roofs i have a few scaffold boards that i have attached old rubber mats to. I place them over the rafters and climb on the roofs, mainly to clear out the leafs that have got under the wall plate trim or lead, but it also helps to push all the crud on the roof away from you rather than dagging towards you from the front. I have also used a tower on a few victorian and georgian roofs, when you havent got the room to move, makes it alot easier with WFP than working off a step ladder. If you are Trad, then get yourself a conservatory ladder, fantastic bit of kit, worth the money if you are doing a few of them over the year.