You have to do one investigation type thing in Higher. Usually the teacher tells you what to do, you do it, and you write it up. Don't think it actually counts for anything.
Higher Physics is awfully mathsy, with lots of formulae to remember, rather than facts.
If you have to crash Higher Physics, a good resource, which is laid out according to the SQA subject specification, is the software package "SURE Higher Physics" which is produced by Counting Thoughts - it can be got from their website. It has simulations that allow you to do investigations.