Hi guys. I need to start saving some cash so I've been trying to figure out if I can set up a direct debit between my HSBC account and an ISA, can anyone tell me if and how to do this?

Thanks a lot!

Not sure you can use a DD for this, but a Standing Order should cover it.
All you need are the ISA account details.

I always advise to use SO's over DD's as YOU are completely in control.