I think that the mathematics in thermal and statistical physics at the level of Schroeder is quite easy. Some derivatives, a logarithm or two (thousand), etc. I would review basic counting (cominatorics) and combinatoric probability. I would also refamiliarize yourself with the ideal gas law. It would benefit you to also review some basic concepts of magnetism (for example, you should know what susceptibility is and know what paramagnetism is) as well as very baby quantum mechanics (the harmonic oscillator and square well energy levels for example, nothing too complicated). Review baby fluid mechanics and pressure.