If I would bite someone in the street, I would be in jail for assault.
We have many different 'grades' of assault in England and Wales but it is certainly Common Assault at the very least and might be an assault causing Actual Bodily Harm (ABH).
I'd do him for unlawful wounding or causing Grievous Bodily Harm (GBH) for which you can get five years, but it's not up to me
Steve