Gaming interview skills – 80/20 advice

I am a contractor, and having moved countries most of my references and connections are now moot. Always been in the top 20% of my colleague pool and confident enough in my skills outside of brainshops like google et al.

It seems in London (my new home) job hunting is heavily weighted towards algorithm tests and whiteboard questions. If I give myself this summer off with a 3 hour a day study window, what is the most effective thing I can do purely to game interview skills.