Do you own a volt meter and know how to use it? You would be able to measure if the battery is at 12 + Volts.

In addition, you can check most of the starter circuit by measure for voltage at the starter solenoid when the ignitiion switch is turned on. Put the + clip lead from the meter onto the small wire connector on the solenoid, and the negative lead to the chassie/ground of the car. When you push the clutch peddle in and turn the ignition key you should see 12 volts on the solenoid. If you do see 12 volts the problem is either the solenoid or starter. If you do not see 12V the problem is back in the starter circuit wiring. I would go back and check the clutch interlock switch.

If you do not have a meter you can remove both the battery and the starter and most auto part stores will test them for you.