Hi @anybody10 I am 76 and am still having treatment for head and neck cancer. This time dental reconstruction.
I don't know what the biopsy surgery will consist of. My guess is that it will be quite brief and you will recover well.
Base of tongue cancer is usually treated with chemoradiation - not a nice treatment at all - about 7 weeks duration. But it shouldn't affect your speech.
My tip would be to have a thoughtful discussion with your medical team after the biopsy about treatment options and your fear about your ability to handle harsh treatment.
So understandable to be frightened. And having to wait until January is awful. Eat and drink as much as you can before your treatment. Eat things you enjoy. It's hard to eat during treatment. Wishing you well.