HI again, Darren
As you are both only 32, you have shed loads of time on your side.
Ho hum! If you plump for a student visa in Oz, financially you will be risking your shirts but if all goes well, you would still be plenty young enough to re-build your capital base out in Oz. That would be the fast track option, albeit financially risky.
On the other hand, if one or both of you undertake re-training in the UK then you could still be in a position to migrate whilst you are still comfortably enough under 45, though your children's ages by then would also be relevant.
I do not know anything about accountancy. Alan Collett of Go Matilda is the expert on that because he is a Chartered Accountant in both jurisdictions as well as being a Registered Migration Agent.
Accountant 2211-11 - Australian Skills Recognition Information
I know that one does not have to be a Chartered Accountant in order to be an "accountant" for migration purposes. I don't know whether there is any qualification short of a British degree that would be considered equivalent to an Australian degree and I have no idea what AAT is so the best thing is to leave me in blissful ignorance about that!
I'm inclined to suggest this: get your wife to ring Alan Collett and pick his brains about what she would need in order to be eligible for one of the Accountant categories for migration.
Meanwhile you pick John Mumford's brain about student visa possibilities and see what he thinks the realistic likely costs-scenario would be like.
Then ask a few others what they would suggest too, I'd say.
I don't think it is possible to do too much research. Find out as much as you possibly can before Christmas and then maybe set some time aside over the holiday period to work out what you think the best game plan for you would be, perhaps?
Best wishes
Gill