Assuming that it is 'ABH', rather than 'Common Assault' or 'GBH', you can read exactly what the magistrates have to read here:
http://www.sentencingcouncil.org.uk/offences/item/assault-occasioning-actual-bodily-harm-racially-religiously-aggravated-abh/
If they see it as only a 'Category 3' offence then a custodial sentence CAN'T be passed. If they see it as a 'Category 2' offence then the 'starting point' sentence is 6 months imprisonment but magistrates generally try to keep first-time offenders out of prison so it's probably more likely that they'd opt for a Community Order. There seems to be little in your post to suggest that 'Category 1' could even be considered.
So, as long as it's only 'ABH' and not (because of the seriousness of the injuries involved) 'GBH', it's probably unlikely that you would go to prison. However if you did manage to inflict serious injuries then aiming a kick at the victim's head would probably be enough to see 'GBH' elevated to 'GBH with intent', making a custodial sentence inevitable.