'Unlawful (malicious) wounding' is an alternative wording to 'grievous bodily harm' for a charge under Section 20 of the Offences Against the Person Act 1861. If the case is heard before a magistrates' court the maximum penalty is 6 months imprisonment (and/or a fine of up to �5000). If the case is passed to the Crown court the maximum penalty is 5 years imprisonment (and/or an unlimited fine). If the offence is racially or religiously aggravated the charge will be under Section 29 of the Act and the maximum period of imprisonment is increased to 7 years.
If the words 'with intent' are added to the charge, it's dealt with under Section 18 of the Act. The case can then only be heard before a Crown court. The maximum penalty is life imprisonment.
For the sentencing guidelines which judges refer to, see this document. (The guideline sentences refer to a first time offender convicted after a trial. An early guilty plea would see the sentences cut by up a one third but previous conviction, especially for violence, could push the sentences higher). The table of guideline sentences for 'Section 20' can be found on page 15. The 'Section 18' guidelines are on page 13:
http://www.sentencing-guidelines.gov.uk/docs/a ssault-against-the%20person.pdf
Chris