In general you use it like that:
- Tenemos "mucho" tiempo para estudiar. (We have a lot of time to study.)
- Tenemos "tanto" tiempo para estudiar "que" podemos descansar un momento. (We have such a long time to study that we can rest for a moment.)
Basically "tanto" is usually followed by "que".
The difference is that "mucho" just gives an idea of a large amount, while "tanto" gives an idea of a large amount, and also we have to add another action.
If we say:
- Tenemos "tanto" de qué hablar. (We have so much to talk about.)
It means that we have a lot of things to talk about, and that maybe time won't be long enough, or that we should continue another day, etc.
- Tenemos "tanto" de qué hablar "que" sería mejor organizarnos. (We have so much to talk about that we should organize ourselves.)
- Hay "muchos" ejemplos para darte. (There are many/a lot of examples to give you.)
- Hay "tantos" ejemplos para darte "que" el mío solo no alcanza. (There are so many examples to give you that mine alone isn't enough.)
I hope this helped you :)