To make a good carbon surface you may work in this way:
sand the tube with a raw grit like 40-
then laminating the layer i mostly use a 245g/m² carbon layer Koeper. Fill it up with epoxy resin and then use a peel off ply wowen
Then you can press the layer with a peel off ply band with a width of 100-
After hardening you have to paint the tube with a fluid resin to close the holes.
After hardening and sanding use a less fluid resin to make the resin layer thicker.
After hardening you can sand the outside smooth with grit 120/240/ 400
Then the tube can be painted with clear or colored varnish
Note in most cases epoxy resin is not UV stabilized and needs a painture!!!
If you have questions please ask.