It would seem you have not actually been charged with anything - were not in America here, you get charged at the end of the investigation, and then bailed to court. you have been arrested on suspicion of committing an offense - in this case section 4A.
A crime is classed as racially aggravated if someone deems it to be, either the victim, the police or a witness. Either will do. So if the victim says that you said a racist comment, then it will be dealt with as a racist incident.
It may not be the crime of the century, but then it is still a crime. the police will investigate any law broken, no matter how big or small. im sure you would expect nothing less.
It seems to me that you can't handle your drink? it is no excuse that you were drunk at the time. If you cant handle your drink properly, and do stupid things, then there s a high chance this will happen again.
If you are ejected from a club, just go, don't struggle - it gives the bouncers an excuse to be more physical as you are not doing what they have asked and they can remove you using whatever force necessary.
I think there is a strong chance you will be charged, 2 door staff have given statements and they have cctv of you struggling with them. You will go to court and if you plead guilty you will get off with nothing much (providing you have a clean record). If you plead not guilty then it will go to trial, they will call all of the witnesses and go through everything in court. there is then a greater chance you will be found guilty and you will get a higher punishment as you did not plead guilty at the earliest opportunity.
The moral of the story, dont get too drunk, do what you are told by the bouncers, and dont say things you are likely to regret.