You would generally need to establish three things to prove negligence:
1. That a duty of care exists;
2. That the standard of care fell below what could be reasonably expected; and,
3. That the harm was forseeable.
Chapters have been written on each of these points many, many times, possibly entire books. You need to consult a solicitor, but yes, I feel you may have a case, depending on the facts and circumstances known, and that may come to light. Your case for the points you made for 2 and 3 are especially interesting.
Your Point 3: If the bouncers were there the club could argue they took reasonable steps to observe the duty of care they undoubtedly owe you. The fact that they were not (if you can prove it) means that the standard of care fell. How low though?
Your Point 2: Plastic v. Glass.
Again, the standard of care seems to have fallen below what should be reasonably expected. Furthermore, in relation to my point 3 (forseeability), the fact that conditions had been imposed to serve drinks in plastic gives the hint that there has been a problem in the past. Has there been previous incidents of a similar nature i.e. 'glassings'. If so, your assault and injury was cerrtainly 'forseeable'. You may have a good case.
In addition, have you looked into Criminal Injuries Compensation? It seems likely that you would be able to submit a successful claim to CICA.
http://www.cica.gov.uk/
Finally, I am very sorry to hear of the damage this attack has caused you. The very best of luck to you and I hope you can find justice.