A Section 39 offence can normally only be heard in a magistrates' court. (There are certain circumstance where the matter can be referred to a Crown court but they don't apply here). The maximum penalty is 6 months imprisonment and/or a �5000 fine.
In practice, common assault doesn't usually result in a prison sentence but 'domestic violence' is seen as an aggravating factor. It would also be an aggravating factor if your husband used, or attempted to use a weapon. However, mitigating factors might include a single blow, an impulsive action, provocation or very minor injury.
It would be for the court to determine the appropriate sentence based upon all of the circumstances which it was made aware of. It's most likely that your husband would be fined and/or given a community punishment, possibly together with an order to attend an anger management course. However, if he's already got a criminal record for violence or, for example, if his attack upon you was a sustained one, it's possible that he might face a short prison sentence of, perhaps, 3 months. (He'd only serve half that time in prison).
I repeat that a non-custodial sentence is probably the most likely but imprisonment can't be ruled out.
Chris