Agree with Dot. However you may find that they say something along the following lines.
The history related to this, sad though it is, has no bearing on any decision that the company will come to regarding employability. The dismissal would be on grounds of capability - not sickness - in that your partner is unable to do his job when he does not attend.
Companies deciding to dismiss must show that they acted fairly, and give contractual notice - clearly they are doing the later - its the former you may be able to question and should be the thrust of the exploration with ACAS. They are obliged to consult, explore reasonable alternatives. But that doesn;t mean they have to find either part-time work for them or different jobs - they would have to explain to him why it isn't practical to do these things.
Don't waste money on your own legal advice - speak to ACAS for free.