Car: L reg 1.4 RT 100k

Been snowing here most of the day, I popped out for a drive at about 9.30pm and after driving through a snow covered carpark my car began to splutter. So i thought it was either just because of the cold or i had got a bit of water in my engine; usually clears itself.
Came to a set of traffic lights and the car stalled, i then started it and had a bit of trouble but managed to get away.
The next lights i came to i managed to keep it running, however the lights after that it stalled. I tried to start the car but it gave out the biggest backfire i've ever heard pulled over with hazards on, gave it a couple of mins and tried again, BANG again!
I then rang a mate and got him to tow me back, now the car wont start at all and has lost at least half of its water from the header tank.

Is it ****ed? if so...i was planning on dropping a valver or Rsi engine in there this summer anyhow...

Thanks, Gav