Will this P channel Mosfet switch work from a 3v3 GPIO
Aside from the driving issue you have (needs a logic-level MOSFET or NPN BJT for Q2, as others have pointed out), your 0-30V is not valid. Nor is the 5A. 

It will need to be at least 4.5V for the Rds(on) to be guaranteed. If it is less than 4.5V heating may even worse than expected. 

Further, even at 4.5V, the power dissipation can be around 5W with a 5A current flowing, which is probably going to be destructive. (40-96°C/W using the PCB layouts given, which means the junction temperature could be well over the absolute maximum). 

A better P-channel MOSFET would help. Also consider measuring the high voltage rail and inhibiting the drive if the voltage is too low.