ah yeah... strangely I wrote my post and then forgot to outline the exact problem... never mind and my mistake. What's going on is when that overhanging part of the model gets printed, or when that part's first layer is printed, it doesn't actually form anything. The material flops down and tangles itself up into a ball rather than forming a line from the rest of the model. When the print has finished, some of the overhang is there however the lower part which was printed first with no layers below it is just a mess and completely unusable. As for stringing, its not really a problem with this model since the nozzle never leaves the walls of the print. Sometimes I get underextrusion however I think I've got that under control now after altering temps, speed, material flow and cleaning out the nozzle (it cant help that my nozzle I'm using is a good 3 or 4 years old and... very well used...). I've just now had a look at the "support blocker" feature of cura and I've got a new gcode file to try using this feature, I think using support and this feature is probably the best solution to my overhang problem. I think i will start using the "ultimaker 2" gcode flavour once again to be able to tune the print live, that was a useful feature. Thanks for your recommendation it has been very useful so far and ill get back to you in a couple days or so when I've got another print done using these new settings.