engine will turn over fine but it will not start, (half full of fuel),

Dont do BMW only do jap cars take it back

firstly 330d does not have spark plugs as its a diesel. The diesel injection systems can play up on them as they are completly electronically controlled.
The immobiliser can disrupt the system, and cause it to not start. Check the glow pugs have power going to them and also that the glow plugs themselves are actually glowing.
If they are, check that they is actually fuel in the fuel filter and that it is getting to the injectors. no other reasons why a diesel should not start