look, it isn't possible for them to exclude him without proving they have given him the support he needs to improve. unless he does something particularly violent or aggressive. we had a child who threw chairs, tables and scissors, and although he had a couple of half day exclusions after incidents, it enabled the school to get the financial support they needed form the lea to provide an understanding 1-1. there are 'behaviour problems' and there are boys that are a bit fidgety and mildly disruptive. unless the school haven't told you an awful lot, they aren't going to be able to exclude him.
whilst you are making your appt with the senco, find out who the sn governor is, and give them a call too. or the chair of govs (sometimes it's the same person) - they will be interested to hear how the school management are dealing with such an alledly disruptive pupil, and interested to hear that they are not going through appropriate provedures before they use the last resort of exclusion...
if they are genuinely planning to exclude your child, they will have to involve the governing body in the process anyway, so best you give them a heads up, anbd ask for some advice in order to prevent it.
senco.
iep with targets.
behaviour plan.
ed psych assessment.
the longer you/ the school take to get these put in place for your son, the more difficult it is going to be.