Depends how you want to do it, for a block course you'd be able to use your AT allowance which is 5 days pa. I've just looked at my local dive centre site and they reckon you can do it in four days , which seems short to me.
If you're doing an internship approach then you fit it in around your work commitments. During ET training you could achieve it in your weekends.
You could use your educational grant to fund part of it as well, since it leads to a recognised qualification.