Checking lounge eligibility for Thai First Class Lounge BKK

[paultiffen]

Hi,

Just triple checking that if my girlfriend is flying Thai First BKK->SYD in Sept next year and I book on a flight to Phuket say then I can access the lounge?

If I then for some reason didn't take this flight would I just show up at the gate and tell them I'm not getting on it.

Thanks
Paul