Any Advice Please
 

Just one ask - if I got a CASA Commercial (OZ) license how easy would it be to come home and become a flying instructor in the UK. I realise to turn a CASA licence into a JAA is quite difficult - but would I need to do this if I was only going to instruct commercially, and did not want an airline job.

Any help really appreciated

The short answer: Yes

The slightly longer answer & rule of thumb: As a general principle you need the local licence to do any paid work *unless* that jurisdiction has made some provision to accept foreign licences and/or you are solely working for an organisation approved by, and operating aircraft registered in, the same jurisdiction as your pilot licence.