The loss of teeth counts as 'ABH'. See the relevant information, from the CPS website, here:
http://www.cps.gov.uk...he_person/#P189_14382
Sentencing guidelines for ABH are on page 17 of this document:
http://sentencingcoun...person_accessible.pdf
The sentences there refer to a first-time offender who is convicted after a trial. An early guilty plea can see a reduction in the sentence. (In the case of a custodial sentence that would be by one third, but that's almost certainly not relevant in your case). A Community Order will be imposed.
Chris