It makes total sense, Mitch. Been there. Most of us have.
You aren't obligated to keep a roof over her head. Alcoholics who get kicked out are very resourceful. I don't know where you live (judging by your writing I'm guessing somewhere in the UK or Australia), but most places have shelters.
Your health and well-being matter. Have you been to Al-Anon? That was a lifeline for me when my second husband went back to drinking after almost dying of it. Ultimately I moved out (we were renting, so I could do that), but if that were impossible, I would have made him leave (that can be complicated, too--depending on the landlord/tenant laws where you live, eviction is sometimes the only way if someone refuses to leave).
Please take care of yourself--stick around here, keep posting, and consider Al-Anon. I hope your g/f decides to get better, but YOU will be better off if you take care of yourself (regardless of what she does).
Hugs,