Welcome to the forum.
As John said, yes.
3-4mm of each side is a wide gap for a couple of coats of paint?
You will need to set up the router table fence to use as a jointer fence.
Check youtube and the forum for a "how to".
BTW, I would not take 4mm off in one pass. I would not take more than 1mm per pass, but others may have other suggestions.
I don't mind if other members disagree with my comments.
I don't profess to know everything, and I may learn something new.
"Never attribute to malice that which is adequately explained by stupidity."