This is troublesome as the machine is only a year old, just gone out of its 1yr warranty. Am I tanked with a machine that is going to cost me a tonne just to repair?
Your screenshot shows a GPU failure in terminal stage. I have seen some. Early stages just show simple horizontal and vertical corruptions, later the colorful squares you have. Your machine could continue working for some time, but any heavy load could end the GPU's life from now on.
I would recommend getting it replaced ASAP. Try an experienced AASP before contacting Apple directly. If they have a good relationship to Apple's folks they may arrange a free repair for you, if it's just out of warranty. If they can't try Apple directly for a discounted repair.