I managed to get it right. I had to make a Rotator from ZX. Make Rot From ZX means Z will always be fixed, which is the ‘up’ vector on the planet, and X will be the direction in which my character face forward. Y will be calculated automatically by cross product of X and Z.
So I get local Z (direction from planet to character
Get the character’s original X (forward vector) so I know what direction to face when standing on the surface.
And finally feed it to my “Make Rot From ZX”
To be honest I thought this forums would have given me this answer in two day’s time.