Cuts simply requiring stitches usually lead to a charge of 'ABH' rather than GBH. See paragraph 46 here:
http://www.cps.gov.uk...he_person/#P189_14382
For a prosecution for 'GBH' to be successful, the type of injuries referred to in paragraph 55 would need to have been sustained.
To see the type of things which can result in 'with intent' being added to a GBH charge (taking it from Section 20 to Section 18), read paragraph 65.
Your barrister will have that same information available to him. By examining the CPS's case, he will be able to see whether it's worth trying to get the charge reduced. If he thinks that it might be possible he will probably approach the CPS barrister to indicate that you'd plead guilty to an ABH charge if the CPS would withdraw the Section 18 one. Otherwise the judge might instruct the jury to consider the alternative charge.
The relevant sentencing guidelines are in this document:
http://www.sentencing...person_accessible.pdf
Those sentences refer to a first-time offender convicted after a trial. Previous convictions can push the sentencing higher. A guilty plea can see the sentence cut. (in the case of a custodial sentence that would be by up to one third).
Refer to page 13 for 'Section 18' (GBH with intent), page 15 for 'Section 20' (GBH) and page 13 for ABH.
Chris