"I am new to body work and I am wondering if any one as an opinion on flexible sanding blocks? "
I think you will find that you will use different hardness blocks for each step of your work from walnut to soft foam sanding pads. Wooden blocks can be made to any size or contour. Check your local paint store for different hardness blocks OR an upholstery shop for foam rubber scraps.
"Hi, try to flexible sanding tools from www.flexicat-tools.com"
A new sanding 'shoe' for a long-board air sander will do the same thing cheaper and it's available at the paint store.
1) Do NOT sand down too far with each grit, you need to remove the heavier sand scratches with the finer grits.
2) use the softer pads with finer grit paper.
Have fun with it