Hell yeah, follow your dreams mate, life is far to short for ifs, buts, or maybes.
You will have great fun with the Zed once you shed a bit of weight and get it set up for track properly.
Fuel, tyres and brakes will be your biggest ongoing outlay.
However once you upgrade the brakes then all you will require is a set of fresh pads periodically.
Get a spare set of Rays and stick a set of slicks on. (In stock at £240.00 for a set of 4)
Sorry, afraid I can't help you with the fuel
Alex.