I am planning to make carbon fiber + nomex honey comb sandwich sheets, about 1.5 m2 pieces. The sheets are not 100% straight, but no radical shapes neither included

If you try To use the honeycomb core without a resin film in one go with pre preg you will starve the carbon of resin giving a poor quality component in strength and looks, a better method would be to used the EC specific adhesive although you could coat the surfaces with a laminating epoxy as a second best option.