I think you need to give us a better idea of what you have in mind, other than what you've already said. The face of the boards you're showing us have curved surfaces, which means they were cut from the sides of the log, which means these boards have sap wood. This may not be of so importance a concern, but something to keep in mind. I suppose the other/opposite faces are flat, no curved areas on the surface. Which sides of the boards are to be the table's top? If the table top is to be of the flatter surfaces, then you wouldn't need the bark on the boards, since it would be unseen, i.e., the option of removing the unnecessary bark.
The boards appear to be nice and solid, however some sapwood may have decayed or is much softer in some (small?) areas, than other areas. Using a wooden mallet or scrap wood, tap on the boards in all areas, listening for a or the different sounds. A dull sound may indicate a weak, soft or potentially rotten area. You may not want a soft area.... you may want to do something about a soft area, if you find one/some. Inspect and study your boards carefully, give them a good evaluation.... if you haven't already.
No matter what finish or epoxy you apply, I don't think you will be able to maintain that weathered gray look, as seen in the pic, of the boards. If you wet the boards with water, the "color" will darken. You will need to clean the boards, so some of the weathered appearance will be removed. With some of the prepping of boards that I have done, there were times when light power washing was a reasonable option. Your boards appear to be in pretty good shape, so I'd suspect just some good stiff brushing may be sufficient, then blow off the dust with an air hose.
With all the cracks and crevices, epoxy coating may very well be your best bet for finish surfacing, especially if you want a smooth flat surface. You will be challenged. Bob is correct, do some practicing. You have some options for prepping and options for finished results. Do some homework and plan well. Don't rush things.
A consideration: However your boards turn out, as per appearance, during the prepping... meaning they are no longer gray/weathered in appearance... all is not lost. There is a simple option for obtaining an old appearance to your boards. For boards as that, you may not need them to have the weathered look for a nice looking table top. The old look may be just as nice. After prepping, if the boards look like normal raw wood, then you can faux age them using a vinegar solution - dissolve steel wool in vinegar and paint it onto the wood. The wood will turn darker, old looking. The degree of darkness achieved will depend on how concentrated the solution is.... Or painting 2 - 3 coats of a mild concentration will darken the wood more with each coat. Practice this technique on some scrap. Samples can darken within 10 minutes of application on hot sunny days.
Sonny
Power washed and planed cypress boards, the raw wood appearance.
https://flic.kr/p/EeRGXJ
https://flic.kr/p/DYbxwL
Faux aged cypress boards, giving the rocker an old appearance.
https://flic.kr/p/2jiJ1E4