The 3 previous convictions are very old and only one is relevant. Is it domestic violence? If so it may be treated differently as the courts are particularly alert to domestic violence offences. That said, Common Assault, contrary to section 39 Criminal Justice Act, is a summary offence which carries a maximum penalty of six months imprisonment and/or a fine. A Community penalty and perhaps a fine or a conditional discharge or suspended sentences seems the most likely. Take a look what other people received for common assault on
http://www.thelawpages.com.