Hi Air bumps,
QF Cabin Crew UK is a separate subsidiary to QF Domestic, QF Link or QF Cabin Crew Australia.
In the UK the requirements are slightly different esp. with regards to the RSA/Senior First Aid.
As Cabin Crew for Qantas Cabin Crew UK, you can't transfer to Australia. So serriously doubt that QF domestic would allow your girlfriend to do her assessment in the UK.
Sorry to be so negative.