//He did not go out to intend to hurt anyone..//
And the police have obviously accepted that and charged him with S20 (GBH without intent) and not the more serious S18 (with intent).
Nonetheless S20 is a serious charge. What is puzzling is that this assault (from your description) does not seem to warrant a charge of GBH. Looking at the CPS charging guidelines I would say that ABH was more appropriate. However, assuming the charge remains as it is, Magistrates do have the option, depending on their view of the seriousness of the offence, to send your husband to the Crown Court (for either trial or sentencing, depending on his plea). However, it seems (again from your description) that the offence is at the lower end of seriousness and they are likely to retain jurisdiction. The “Starting Point” is a High Level Community Order and there does not seem to be any factors to move it significantly away from that. The Magistrates will require a report from the probation service to assist with sentencing. The Community Order could include supervision by the probation service, unpaid work or a curfew.
Your husband should note that at his first appearance only he will be entitled to see the duty solicitor at court. He might like to take advantage of that right (unless he intends to instruct his own solicitor). The duty solicitor may be willing to have a chat with the prosecutor to see if a lesser charge (ABH) might be put. However, in view of the injuries sustained I cannot see agreement to bringing the charge down to Common Assault.