All bolts are undone, starter motor is out, I have approx 10mm of separation, but alas it won't go any further..... Need help pls...cheers

Hi Newbie.   Always helps to state which vehicle. I will assume SW20 manual trans. 
If the 10mm separation is even all round then its probably hung up by the splines of the gearbox input shaft in the clutch friction disc.  Push gbox back on and jerk it out a couple of times. Hopefully it will eventually let go.

Also try to lift the weight of the box off the input shaft while pulling the box off. You doing this in the vehicle?