I also wanted it to hold hot liquids, not crack or leak.
I'm pleased to say its passed and working well. I made up a pine pitch using Pine resin, beeswax and ground charcoal for the suspect knots, and oiled the outside with Rapeseed oil.
It holds 350ml to the brim so theres a bit of room spare for movement which allows me to wake up in the morning with a good strong large coffee :) This will be my new camping buddy.
Frosts 106 knife for scale
and the repair and test...