I can't understand a word of what happened but, S18 is GBH WITH Intent .
GBH WITHOUT intent is section 20.
Section 18 is always a prison sentence, section 20 gives you a chance of a non custodial sentence though prison is still possible.
Section 18 is a lot more serious, you really need to be sure which one you are charged with. S 18 or S 20.
If I understand correctly you left the pub after a fight, went home and got a hammer, while heading back to the pub with the hammer you were arrested.
Sorry, that looks to me like Section 18, you are looking at around 3 years in prison, your 'previous' will count against you even though it was not for violence.