Courts can only suspend a sentence if the period of that sentence is one of less than 12 months:
http://open.justice.gov.uk/how-it-works/#d
Since the absolute minimum sentence which can be passed by a court for a 'Section 18' offence (other than in really exceptional circumstances, such as the offender having a terminal illness) is one of 2 years imprisonment, it would seem impossible for a suspended sentence to be passed.
http://sentencingcouncil.judiciary.gov.uk/docs/Assault_definitive_guideline_-_Crown_Court.pdf
(See pages 3 to 6. You need to deduct one third from the sentences shown there if your fiancé pleaded guilty at the earliest opportunity).
Further a judge would not remand an offender into custody, pending sentencing, unless he/she was wholly confident that an immediate custodial sentence would be passed.
While it would be technically possible for a judge to pass a sentence of less than 12 months, and then to suspend that sentence, I can't see it being a realistic possibility. The judge would have to explain (in open court) why he had gone against the official guidelines (which are in my second link above) and I can't see that he/she would have any real grounds to do so. Further, offending through drunkenness is more likely to increase sentencing than to reduce it.