It doesn't need to be blocked for some laptops. The fact that you put it on a wood table means that it can't conduct heat away fast enough even with the fan working.
If you type perfmon /res in the search folders and files box it will come up with the cpu load etc.
If you then go to CPU you will be able to see whats going through it.
With nothing running ie blank dersktop etc nothing should be over 20% if your average is sitting up at 60% + you need to find out whats doing it.