Currently my sub panel in the garage is supplied by 10 gage 2 wire with ground from a 30 amp dbl pull breaker in the house. The run is 30' to the 100 amp box in the garage. The garage is a part time workshop with several power tools on at the same time along with 10 4' fluorescent light fixtures and a ele space heater. Is the gage correct?

Is the gauge correct for a 30 amp circuit? Yes.

Perhaps the question should be is 30 amps enough for the load to be served in the garage.

That I doubt, but to say definitely, I need to see the total load in amps or wattage, or list the load of each device.

With what you have or planned with the 30 amp and #10 wire, you can have a total load of 26 amps at any one time.