Really, honestly, it's better to stay in from now until January and re-emerge when it's easier to get served at the bar. If, however, you want to have a life between now and Christmas, you have to think tactically to avoid The Amateurs:
1. Think Other Cultures' food. Especially those who refuse to join in - think hardcore non-Santastic - like Pakistan, Eritrea or Malaysia. I have a Malaysian restaurant just up the road from me that won't allow alcohol in the door, where they mutter about 'unbelievers' if you so much as hum a Christmas Carol. Great food, too.
2. Think Sport. Even gyms have annoying Christmas carols oozing, so try swimming. And if you see anyone swimming in a Santa hat - drown them.
3. Think Art. David Teniers and The Theatre of Painting at The Courtauld Institute of Art should restore some propriety to your world.

Now all you have to is sort out those last minute presents. Relax, there is thing called Internet Shopping, and these retailers guarantee to deliver before Christmas: