"Yes, I have been charged via Postal Requisition and hearing will take place at the Magistrates Court."
Then have you been served with the "Initial Details of the Prosecution Case" (IDPC)? You must be provided with this before you enter your plea (and in a reasonable time to enable you to study it or have it studied by a solicitor - handing it to you on the day of your first hearing is not satisfactory). This should contain the statements and any other material the prosecution intends to rely on to secure a conviction. If you have that, what does it contain?
When you have it I recommend you consult a solicitor. If they go to trial these "I said, he said, I did, he did" cases are notoriously difficult to handle as a defendant. It requires cross-examination of prosecution witnesses which is a skill even some lawyers have difficulty properly mastering. You will be able to take advantage of the “duty solicitor” service on your first appearance only. He or she will be able to look at the evidence against you and advise you on your plea. But for subsequent hearings you will have to arrange your own representation. Your local Citizens Advice Bureau should be able to provide you with a list of local solicitors who will provide a free initial consultation (and contrary to Eddie’s advice, not all do). If you plead Not Guilty and are acquitted you should be able to claim your defence expenses but at Legal Aid rates only (which again is somewhat different to Eddie’s advice).
On a practical note, ABH is an "either way" offence, meaning it can be dealt with either in the Magistrates' Court or the Crown Court. From your description of events it appears to be at the lower end of seriousness and I suspect the Magistrates' will agree to retain jurisdiction. However, if you plead not guilty you have the right to a trial in the Crown Court before a judge and jury. The duty solicitor will explain all this to you.