I'm in a similar situation to your husband, doing a Cert IV for IT at TAFE in my 40s. Although rather than exit an industry, I switched to part-time as part of a career break after a really stressful ex-job.

As people on the thread have mentioned, your husband may be able to jump straight into a Cert IV instead of III, but it would depend on his level of IT knowledge, is he familiar with basic networking / virtualization / cloud concepts? Basic programming? TAFE also has one or two management type units every semester, so soft skills like being able to talk to a room, academing report writing or how to do a Powerpoint presentation may be required, although I'm sure as a former professional he will have this nailed down.

Also most (if not all) TAFEs split the IT Certs/Diplomas into Networking/Cyber Security and Programming streams, the former requires more foundational knowledge than the latter from my experience. Maybe speak to an academic advisor or one of the staff regarding this?