>>>If the guy drops his charges can I still get done?
As far as the Crown Prosecution Service is concerned, offences such as GBH always have TWO 'victims'. One is, obviously, the person who was injured but the other is 'public order' (or, if you prefer 'the law of the land'). Even if the (physical) victim doesn't seek a prosecution the CPS will still seek a conviction unless there is then insufficient evidence for them to do so. (Given that there'sclear CCTV evidence, that would seem to be unlikely).
The test for 'GBH' (either as a 'Section 20' offence or a 'Section 18' one) is simply based upon the severity of the injuries sustained. For a GBH conviction those injuries must be 'really serious', with the CPS website giving the following examples of what can constitute 'really serious':
injury resulting in permanent disability, loss of sensory function or visible disfigurement;
broken or displaced limbs or bones, including fractured skull, compound fractures, broken cheek bone, jaw, ribs, etc;
injuries which cause substantial loss of blood, usually necessitating a transfusion or result in lengthy treatment or incapacity;
serious psychiatric injury. As with assault occasioning actual bodily harm, appropriate expert evidence is essential to prove the injury
If the injuries are (as above) serious enough for a 'GBH' charge, the CPS then have to decide whether 'with intent' can be added to the charge (raising it from 'Section 20' to 'Section 18'). The CPS website states:
"Factors that may indicate the specific intent include:
a repeated or planned attack;
deliberate selection of a weapon or adaptation of an article to cause injury, such as breaking a glass before an attack;
making prior threats;
using an offensive weapon against, or kicking the victim's head"
Source:
http://www.cps.gov.uk/legal/l_to_o/offences_against_the_person/
When someone is convicted of GBH (either as Section 20 or Section 18 "with intent"), the judge then has to decide whther the offence falls within 'Category 1', 'Category 2' or 'Category 3'.
It's Category 1 if both 'harm' and 'culpability' are 'high'. If only one of those factors is 'high', and the other low, it's 'Category 2'. If they're both 'low' it's 'Category 3'.
The ONLY type of GBH conviction that can result in a non-custodial offence (unless the judge finds exceptional reasons to enable him breach the official guidelines) is a Section 20 one at Category 3. Otherwise imprisonment is a certainty.
Staying with Section 20, the 'starting point' sentence for Category 2 is 18 months imprisonment. For Category 1 it's 3 years.
If the conviction is under Section 18, the 'starting point' sentences are as follows:
Category 3: 4 years
Category 2: 6 years
Category 1: 12 years.
Source:
http://sentencingcouncil.judiciary.gov.uk/docs/Assault_definitive_guideline_-_Crown_Court.pdf
Based upon your account of things, your best chance of avoiding imprisonment is to hope that you solicitor/barrister can get the charge dropped to 'ABH'. However you still need to be aware that 'affray' (on its own, before any actual assualt charge is added on) often results in a custodial sentence.