Covering up scars and tatoos

I’m hoping that the wealth of knowledge out there will have some ideas. I’m 8 months post surgery (WLE and sentinal nodes) and 4 post rads and am looking at my party frocks and all leave scars or tatoos showing, particularly the scar under the arm that goes round to the front, and the tatoos on the chest.
Has anybody found anything that can effectively cover scars up without disappearing/dissolving?