We have a 15 week old jack russell puppy I need to know how to stop him going to the toilet during the night

He is still a baby, if he has to go at night, he can't hold it till you wake up. Once he gets older things change.

Take him out before you go to bed and wait until he goes, that might help some. Get him on a schedule with food and you will know when he needs to go.

Still all night is a lot to ask for.:)