Georgia,
My situation is the other way round to yours! (Lung primary, mets to jaw) and it was jaw symptoms which sent me to the docs in the first place.
Mine is also 'aggressive' and inoperable, incurable, but I was offered chemo straight away to try and halt/slow the growth--which so far seems to have happened.
Like Melissa, the treatment hasn't been anything like as awful as I anticipated and I've had a good quality of life for the last 4 months. I am waiting now for next review and CT scan on Sept 4th.
Where are you being treated in the UK?
I am 20 years older than you and can only imagine how you must be feeling with a similar prognosis.
Feel free to email me if you want,
Brenda

Brenda in UK--Diagnosis 30/5/07--undifferentiated carcinoma in right jawbone and muscles. Stage 4
6/7/07--new diagnosis primary is in lung. Finished 4cycles of palliative carboplatin/gemcitabine
therapy September 07
Now dying to live!