Unless there are genuinely exceptional circumstances, judges must sentence first time offenders, convicted after a trial under 'Section 20', as follows. (In each case there's a 'starting point' sentence. The judge starts from there and then moves the sentence up or down, within the constraints shown, depending upon the circumstances of the case):
No weapon used, no pre-meditation, no particularly grave injuries or disfigurement:
SP = 24 weeks. Min = High level community order. Max = 36 weeks.
As above except assault was pre-meditated:
SP = 36 weeks. Min = 24 weeks. Max = 18 months.
Pre-meditation plus the use of a weapon OR other assault where particularly grave injury was inflicted:
SP = 18 months. Min = 12 months. Max = 3 years.
Pre-meditation, use of a weapon & particularly grave injury or disfigurement:
SP = 3 years. Min = 2 years. Max = 4 years.
It should be noted that kicking someone (while wearing shoes or boots) can be regarded as the 'use of a weapon'. It should also be noted that, in the event of a custodial sentence being passed, the actual time spent in prison is normally half of the nominal sentence.
Chris