Ok so im doing some work this weekend on the car putting injectors in cleaning air intake etc
I wonder if there is anything I can get to paint on the throttle body heat reflective paint to help keep the air cold?

Simply put.......No

not so simply put....

there are heat reflective paint available in spray cans. however they wont work they way u want them to. your throttlebody is alluminium (a great conductor of heat) which means it will get heat soak from anything nearby. Your engine bay temps can get as hot as 80/90degrees C.

Also i beleive your throttle body has coolant lines that go into it that are actually used to Heat it up. This is used to actually speed up the flow of air, if the air coming into the airbox is cooler, and then it is heated at the t/b it will expand and actually flow faster. (much the same way that wrapping a turbo dump pipe in exhaust wrap has great benefits for exhaust flow as the heat is contained within the pipe and the air flows through it faster)
heating the throttle body also helps your car warm up on a cold morning and the hotter air assists in fuel atomisation.