Magistrates only send cases to the Crown Court when they believe that their sentencing powers might not be great enough. (Pedants might point out that there can be other reasons why magistrates would send a case to the Crown Court but they're almost certainly not relevant to this type of case). So that means that the magistrates were of the opinion that the offence might result in a sentence of greater than 6 months imprisonment. However it's worth noting that Crown Court judges often don't concur with such views; many cases referred up to the Crown Court still end up with a non-custodial sentence (or a custodial one of less than 6 months).
The judge will have to examine the issues of 'harm' and 'culpability' to decide whether each of them will be classed as 'higher' or 'lower'. If they're both seen as 'lower' then a custodial sentence can't be imposed for an ABH offence. If they're seen as 'one of each' then a non-custodial sentence is possible for ABH but the 'starting point' sentence, from which a judge has to work up or down, is one of 6 months imprisonment. If they're both seen as 'higher' then a custodial sentence is inevitable (with a 'starting point' of 18 months imprisonment).
In a domestic violence case it's likely that 'culpability' would be seen as falling into the 'higher' category. If your injuries were relatively minor (within the range which constitutes 'ABH') then 'harm' might be seen as 'lower'. If your injuries were close to the 'GBH' level harm would be 'higher'.
If we assume 'culpability' = 'higher' and 'harm' = 'lower', the judge will work from the 'starting point' I've mentioned of 6 months imprisonment. An early guilty plea could have seen that cut by a third, to 4 months, but the belated one might only take it down to 5 months. The previous convictions might then take the sentence up to round 8 months imprisonment, which (given the very limited information we've got before us) is the best guess that I could make. [The actual time he'd be 'banged up' for would only be 4 months].
See pages 11 to 14 here to read exactly what the judge will have before him:
https://www.sentencingcouncil.org.uk/wp-content/uploads/Assault_definitive_guideline_-_Crown_Court.pdf
If the value of the criminal damage is relatively small (such as breaking a mobile phone, rather than knocking down a house with a digger) it can probably be effectively ignored here, as it would only result in a fine or other non-custodial sentence. (Even if the value of the criminal damage was higher then, unless it was really massive, any custodial sentence would probably run concurrently with that for ABH anyway).