...what do I need to convert to what If I'm intending to work as an instructor within the UK?
As things stand at present, nothing. Your licence and all of your ratings and certificates are issued and administered by the UK as this is the state that currently holds your medical records - that's the way EASA works. However, you can undertake the training and testing for the licence, ratings and certificates in any member state. You will receive a certificate from Austro-Control showing the exams that you have passed and this will be submitted to the UK CAA in support of your application for the FI Certificate.
Whopity just beat me to it.