Overheated, lost coolant and broke down!!! What is wrong with it this time??

[Miller350z]

Hi, hoping for a bit of advice/help. Car has never overheated whilst I have owned it. It was 27°c yesterday, may car had been sat for 8 hours. I got in to drive home. Going through town at 30-40mph. Got approximately 5 miles, around 12 mins driving and the engine management light came on, it juddered like hell and had no power. I pulled up and it smelt hot. I could hear a hissing/whinning noise. Opened the bonnet and coolant was coming from the header tank. Header tank was now empty. Waited for it to cool down. Topped rad up with water and nothing came from bleed screw. Topped up bleed screw and water came from rad cap filler hole. Drove home and left it.

I'm thinking....

1) blocked rad

2) thermostat

3) water pump

4) air in system

5) head gasket!!!

I had a p1217 code 

Any help would be good.

Thanks