Ive done 5 tracksdays, still on the original back tyres, and would still be on the original brakes, if I had not upgraded them. So, it really depends how hard to push it. I don't hang about, but I don't over do it!
A good way through my second set of tyres, but bare in mind that my car is 1.5 years old with 16k+ miles, and with alot of torque through the front wheels.