It'd be a good idea to check what tools/frameworks the company uses so you can start getting familiar - it's possible they'll ask questions about those or give you a small sample application to write with them.
Nothing wrong with searching for coding interview tasks, seeing if you can solve them before seeing answers, and making sure you can explain your reasoning/choices.
Don't forget an interview is a two-way thing - they're trying to determine if you're a good fit, but you should also be looking to determine if it's the right team/company for you, what opportunities will they provide, and so on.
To a large degree language doesn't matter - it's knowing the abstract concepts and how to combine them that makes people [good] programmers.
Interesting that they let you use your own laptop - suggests they understand the importance of a developer having tools tweaked for their own use.